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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

Another family wedding where my eldest is excluded - a year on

876 replies

Stuckinthemiddlewithnoone · 26/04/2025 15:20

12 year old wants to go to wedding where sister hasn't been invited | Mumsnet

This was my thread from almost a year ago and it's happened again.

Younger one invited but not older one, this time the brother of the original groom.

Younger one went with her gran and the rest of the family and we stayed at home. It's set a horrible precedent.

My husband isn't doing anything and younger one going on her own again.

The family clearly want to make some bizarre point.

I genuinely believed that this wouldn't happen again, only last week husband was at his mother's with the father of the groom and nobody said anything. My mother-in-law won't get involved but thinks we made too much of an issue last time and we should have asked for an invitation grovelled for my eldest daughter instead of declining with dignity.

I don't think this is against my daughter, I think this is payback for last time.

12 year old wants to go to wedding where sister hasn't been invited | Mumsnet

Essentially we have declined an invitation to husband’s nephew’s wedding in the summer as he has not invited my 15 year old daughter (16 by the time o...

https://www.mumsnet.com/talk/am_i_being_unreasonable/5069694-12-year-old-wants-to-go-to-wedding-where-sister-hasnt-been-invited

OP posts:
nomas · 28/04/2025 11:13

Ponoka7 · 28/04/2025 09:14

'They' as in the person sending out the invites, didn't know what they were doing. As said, the OP and her DH decided to go for drama and fall out, rather than let the bride know of her mistake and for her to rectify it.
No-one would be arsed with that, on top of organising a wedding.
I was the child that was cut off from biological family because the adults should have taken emotion out of decision making. As adults my half-sister reconnected with her family and now has cousins etc galore. While I know none of my blood relatives and no, I haven't been accepted into my sister's family, because I'm not family. The OP and her DH have set the tone, now they have to live with it. I pity DD2 because if there is a 21st birthday party, wedding and Christening etc, it sounds as though her parents will see it as another occasion to cause drama over.

This is an interesting perspective. I’m sorry that happened to you.

I’m also noting the lack of sympathy to you on this thread. As you will see, many people only care about children from the first wife for some reason.

SpookyMcTaggart · 28/04/2025 11:23

Horrible excluding behaviour, no excuse for it at all. The answer is simple - either both girls are invited to the wedding and made welcome, or neither of them will be attending.

nomas · 28/04/2025 11:24

Munnygirl · 28/04/2025 10:49

It’s the inlaws who have set the tone not the op

Edited

It’s bizarre that these grooms are even telling their future wives that dd1 is a step-dd.

When I met my DH, I told him I have x cousins. I didn’t even feel the need to tell them which ones are adopted, which are step and which are half. He knows now but it would never have been a consideration for our wedding. Everyone was invited because they’re all family.

So the grooms have set the tone here, in my view.

Ladybirdflyawayhome · 28/04/2025 11:28

I think you have a MIL problem. Clearly your eldest daughter is not regarded as family. MIL could sort this but doesn’t want to.

nomas · 28/04/2025 11:34

Ladybirdflyawayhome · 28/04/2025 11:28

I think you have a MIL problem. Clearly your eldest daughter is not regarded as family. MIL could sort this but doesn’t want to.

Ah it’s cherchez la femme again. The MIL has said she wants both DGDs at the wedding. The groom is not her son, she cannot control who he invites!!!

winnieanddaisy · 28/04/2025 12:12

I can’t understand people who do this to children . When my DS2 married his wife already had a DD of about 6 years old . A year later DS1 got married in Greece none of the family could afford to go to Greece for 2 weeks for the wedding but we too this step grandchild with us for the holiday . Not only could she attend the wedding but the couple decided that she could be a bridesmaid. This is what close families do .

SerafinasGoose · 28/04/2025 12:19

MellowCritic · 28/04/2025 07:33

BiL doesn't want any issues between us. The conversation moved on about youngest and BiL spat out that MiL hadn't even been allowed to be alone with youngest daughter for seven years... and that eldest was always there. MiL was never stopped ever from seeing youngest and as for eldest always being there, well where else would she have been?

Op I'm sorry but your husbands family sound pathetic and childish and their thought process is nasty. And why exactly does mil need to be alone with one child.. she just sounds controlling and batshit. Your youngest does seem to be taking from their side with no loyalty to her sister.. personally my sister comes number one to some cousin or a wedding but I guess she's only young and ultimately it's up to her...

Edited

Indeed. It's DD1's home. What does the MiL expect: that the girl should wait in the outhouse until she's finished having her quality time with DD2?

Other information coming through loud and clear in OP's posts is that:

The two sisters have a good relationship and get on well;
DD2 is not engaged in a game of one upmanship with her elder sister, and is supportive of her;
DD2 is always in and out of granny's house;
DD2 is very settled in her attitude of 'this is my family, not hers', adheres rigidly to that view (probably in the face of significant family opposition) whenever a family event comes up from which her sister is excluded, and is not shy of firmly and confidently stating that opinion;
This attitude has only become apparent when DH's family require her presence (and DD1's absence) from specific family events.

Taking these points together, it's not too much of a stretch to deduce who has been getting into DD2's earhole about all this. The attitude and influence she is possibly repeating echoes precisely BiL's complaints about MiL wanting DD1 to 'disappear' from her own home, and other grievances about what MiL can and cannot do with her own grandchild - whom it appears she regularly sees in her own home in any case. Is it likely BiL took gratuitous offence on her account from his own observation, or are these complaints she's been making to other family members? That one's a no-brainer.

This is supposition, but it's not supposition wholly without background facts to substantiate it. IF, however, it's even partially correct then I would disagree with the posters claiming Granny is a benign influence who is doing no harm to OP's family unit. Divisive behaviour like this does do harm, and greatly so. Already, it's put OP in an unenviable position more than once, is instilling exactly the wrong attitudes in young children still of an impressionable age, and most seriously, is pitting two sisters against one other who have previously enjoyed a positive, mutually supportive relationship.

From my perspective, this may very well fall into the category of unforgiveable.

MellowCritic · 28/04/2025 12:22

SerafinasGoose · 28/04/2025 12:19

Indeed. It's DD1's home. What does the MiL expect: that the girl should wait in the outhouse until she's finished having her quality time with DD2?

Other information coming through loud and clear in OP's posts is that:

The two sisters have a good relationship and get on well;
DD2 is not engaged in a game of one upmanship with her elder sister, and is supportive of her;
DD2 is always in and out of granny's house;
DD2 is very settled in her attitude of 'this is my family, not hers', adheres rigidly to that view (probably in the face of significant family opposition) whenever a family event comes up from which her sister is excluded, and is not shy of firmly and confidently stating that opinion;
This attitude has only become apparent when DH's family require her presence (and DD1's absence) from specific family events.

Taking these points together, it's not too much of a stretch to deduce who has been getting into DD2's earhole about all this. The attitude and influence she is possibly repeating echoes precisely BiL's complaints about MiL wanting DD1 to 'disappear' from her own home, and other grievances about what MiL can and cannot do with her own grandchild - whom it appears she regularly sees in her own home in any case. Is it likely BiL took gratuitous offence on her account from his own observation, or are these complaints she's been making to other family members? That one's a no-brainer.

This is supposition, but it's not supposition wholly without background facts to substantiate it. IF, however, it's even partially correct then I would disagree with the posters claiming Granny is a benign influence who is doing no harm to OP's family unit. Divisive behaviour like this does do harm, and greatly so. Already, it's put OP in an unenviable position more than once, is instilling exactly the wrong attitudes in young children still of an impressionable age, and most seriously, is pitting two sisters against one other who have previously enjoyed a positive, mutually supportive relationship.

From my perspective, this may very well fall into the category of unforgiveable.

Edited

Nailed it!

Munnygirl · 28/04/2025 12:39

SerafinasGoose · 28/04/2025 12:19

Indeed. It's DD1's home. What does the MiL expect: that the girl should wait in the outhouse until she's finished having her quality time with DD2?

Other information coming through loud and clear in OP's posts is that:

The two sisters have a good relationship and get on well;
DD2 is not engaged in a game of one upmanship with her elder sister, and is supportive of her;
DD2 is always in and out of granny's house;
DD2 is very settled in her attitude of 'this is my family, not hers', adheres rigidly to that view (probably in the face of significant family opposition) whenever a family event comes up from which her sister is excluded, and is not shy of firmly and confidently stating that opinion;
This attitude has only become apparent when DH's family require her presence (and DD1's absence) from specific family events.

Taking these points together, it's not too much of a stretch to deduce who has been getting into DD2's earhole about all this. The attitude and influence she is possibly repeating echoes precisely BiL's complaints about MiL wanting DD1 to 'disappear' from her own home, and other grievances about what MiL can and cannot do with her own grandchild - whom it appears she regularly sees in her own home in any case. Is it likely BiL took gratuitous offence on her account from his own observation, or are these complaints she's been making to other family members? That one's a no-brainer.

This is supposition, but it's not supposition wholly without background facts to substantiate it. IF, however, it's even partially correct then I would disagree with the posters claiming Granny is a benign influence who is doing no harm to OP's family unit. Divisive behaviour like this does do harm, and greatly so. Already, it's put OP in an unenviable position more than once, is instilling exactly the wrong attitudes in young children still of an impressionable age, and most seriously, is pitting two sisters against one other who have previously enjoyed a positive, mutually supportive relationship.

From my perspective, this may very well fall into the category of unforgiveable.

Edited

Totally this ⬆️

Feelingmuchbetter · 28/04/2025 13:00

Munnygirl · 28/04/2025 12:39

Totally this ⬆️

Yes I agree perfectly put by pp. 100% agree with this summarising of the situation.

InterIgnis · 28/04/2025 13:15

SerafinasGoose · 28/04/2025 12:19

Indeed. It's DD1's home. What does the MiL expect: that the girl should wait in the outhouse until she's finished having her quality time with DD2?

Other information coming through loud and clear in OP's posts is that:

The two sisters have a good relationship and get on well;
DD2 is not engaged in a game of one upmanship with her elder sister, and is supportive of her;
DD2 is always in and out of granny's house;
DD2 is very settled in her attitude of 'this is my family, not hers', adheres rigidly to that view (probably in the face of significant family opposition) whenever a family event comes up from which her sister is excluded, and is not shy of firmly and confidently stating that opinion;
This attitude has only become apparent when DH's family require her presence (and DD1's absence) from specific family events.

Taking these points together, it's not too much of a stretch to deduce who has been getting into DD2's earhole about all this. The attitude and influence she is possibly repeating echoes precisely BiL's complaints about MiL wanting DD1 to 'disappear' from her own home, and other grievances about what MiL can and cannot do with her own grandchild - whom it appears she regularly sees in her own home in any case. Is it likely BiL took gratuitous offence on her account from his own observation, or are these complaints she's been making to other family members? That one's a no-brainer.

This is supposition, but it's not supposition wholly without background facts to substantiate it. IF, however, it's even partially correct then I would disagree with the posters claiming Granny is a benign influence who is doing no harm to OP's family unit. Divisive behaviour like this does do harm, and greatly so. Already, it's put OP in an unenviable position more than once, is instilling exactly the wrong attitudes in young children still of an impressionable age, and most seriously, is pitting two sisters against one other who have previously enjoyed a positive, mutually supportive relationship.

From my perspective, this may very well fall into the category of unforgiveable.

Edited

Mil being able to spend time with just her granddaughter would not have required the older sister to wait in an outhouse.

It is not ‘harmful’ to recognize that while the two girls may be sisters, they are not the same. They do not share paternal family, and their respective relationships reflect that. OP’s youngest should not be expected to sacrifice the relationships she has in a misguided show of ‘loyalty’ to her sister, as if her sister lacking them means that she should have to miss out too. That is a massively unfair burden to place upon her.

That OP’s daughter doesn’t have the same is not the fault of OP’s in laws or youngest daughter, and not something they should be expected to take responsibility for.

Munnygirl · 28/04/2025 13:31

InterIgnis · 28/04/2025 13:15

Mil being able to spend time with just her granddaughter would not have required the older sister to wait in an outhouse.

It is not ‘harmful’ to recognize that while the two girls may be sisters, they are not the same. They do not share paternal family, and their respective relationships reflect that. OP’s youngest should not be expected to sacrifice the relationships she has in a misguided show of ‘loyalty’ to her sister, as if her sister lacking them means that she should have to miss out too. That is a massively unfair burden to place upon her.

That OP’s daughter doesn’t have the same is not the fault of OP’s in laws or youngest daughter, and not something they should be expected to take responsibility for.

Should they have just left the older daughter at home alone then?

SerafinasGoose · 28/04/2025 13:34

InterIgnis · 28/04/2025 13:15

Mil being able to spend time with just her granddaughter would not have required the older sister to wait in an outhouse.

It is not ‘harmful’ to recognize that while the two girls may be sisters, they are not the same. They do not share paternal family, and their respective relationships reflect that. OP’s youngest should not be expected to sacrifice the relationships she has in a misguided show of ‘loyalty’ to her sister, as if her sister lacking them means that she should have to miss out too. That is a massively unfair burden to place upon her.

That OP’s daughter doesn’t have the same is not the fault of OP’s in laws or youngest daughter, and not something they should be expected to take responsibility for.

A lot of hyperbole to unpick here.

I nowhere suggested that DD2 should be expected to 'sacrifice' her familial relationships. The OP's post was about two wedding invitations specifically excluding one member of her family unit. Had the parents alone been invited, without either child, no one would have thought further of it. 'Child-free' weddings are an accepted norm. Conversely, singling one child out for exclusion is vindictive, unnecessary, and should by no means be encouraged.

It's a parent's duty to protect their family unit from manipulative, divisive behaviour with potentially serious repercussions. OP is trying her damndest to do her best by both daughters, but in this regard she made a mistake and it's now led her to the same untenable position she was in a year ago. Her husband doesn't exactly help matters.

There is a lesson to be learned here about family loyalty, and this situation provides a good opportunity to teach it. At twelve years of age it's to be reasonably expected that DD1 would abide by the directives of her parents. Not allowing her to attend one wedding is not 'making her suffer'; no one's telling her her relationship with these troublemaking relatives is off-limits. But encouraging division between two previously close and supportive sisters is very likely to cause future suffering to both.

It's interesting that you consider any loyalty on DD2's part toward her own sister to be 'misguided', whereas loyalty to her granny and extended cousins is perfectly understandable. I'm curious as to how you have reached that somewhat illogical conclusion.

InterIgnis · 28/04/2025 13:35

Munnygirl · 28/04/2025 13:31

Should they have just left the older daughter at home alone then?

I wasn’t aware that both parents were required to take the youngest to MIL’s house.

InterIgnis · 28/04/2025 13:59

SerafinasGoose · 28/04/2025 13:34

A lot of hyperbole to unpick here.

I nowhere suggested that DD2 should be expected to 'sacrifice' her familial relationships. The OP's post was about two wedding invitations specifically excluding one member of her family unit. Had the parents alone been invited, without either child, no one would have thought further of it. 'Child-free' weddings are an accepted norm. Conversely, singling one child out for exclusion is vindictive, unnecessary, and should by no means be encouraged.

It's a parent's duty to protect their family unit from manipulative, divisive behaviour with potentially serious repercussions. OP is trying her damndest to do her best by both daughters, but in this regard she made a mistake and it's now led her to the same untenable position she was in a year ago. Her husband doesn't exactly help matters.

There is a lesson to be learned here about family loyalty, and this situation provides a good opportunity to teach it. At twelve years of age it's to be reasonably expected that DD1 would abide by the directives of her parents. Not allowing her to attend one wedding is not 'making her suffer'; no one's telling her her relationship with these troublemaking relatives is off-limits. But encouraging division between two previously close and supportive sisters is very likely to cause future suffering to both.

It's interesting that you consider any loyalty on DD2's part toward her own sister to be 'misguided', whereas loyalty to her granny and extended cousins is perfectly understandable. I'm curious as to how you have reached that somewhat illogical conclusion.

The irony.

OP’s youngest is nearly 14, and fully capable of forming her own opinions that may or may not be shared with her mother.

She attended the wedding last year under the same circumstances, despite OP’s opposition and attempts to teach her said ‘valuable lesson’. Thankfully, she is supported by her father to do the same this year.

She has spent her entire life being encouraged to form close bonds with her paternal family, and she has done just that. She loves them, and they are important relationships for her (evidenced by the fact she in and out of their houses weekly). She exists independently of her sister, and her sister’s lack of paternal family hasn’t prevented, and shouldn’t prevent, her from actively participating in hers.

Expecting her to ‘take a stand’ for her nearly adult sister now will not teach her ‘loyalty’, it will only cement resentment (which even OP acknowledges, and given that she knows her daughter she’s unlikely to be wrong) it which is hardly conducive to either a good sibling relationship or a mother - daughter one.

Her older sister is not their family in the way that she is. That isn’t her fault, any more than it is the in laws fault. DD1’s lack of paternal family is the fault of her paternal family alone, and is not something the younger daughter and her family should be expected to either provide to her, or pay for.

DraigCymraeg · 28/04/2025 14:24

Bigfatsunandclouds · 26/04/2025 15:57

I thought the first time was cruel but doing it a second time knowing how much upset it caused is unforgivable in my eyes. I wouldn't let younger child go this time.

Absolutely. Why on earth would part of the family attend?
They should all stay away.

Ruthierainbow · 28/04/2025 14:26

Everyone goes or no one goes is my best advice. It's not unreasonable to expect your family to be included as a whole .

Feelingmuchbetter · 28/04/2025 14:45

InterIgnis · 28/04/2025 13:59

The irony.

OP’s youngest is nearly 14, and fully capable of forming her own opinions that may or may not be shared with her mother.

She attended the wedding last year under the same circumstances, despite OP’s opposition and attempts to teach her said ‘valuable lesson’. Thankfully, she is supported by her father to do the same this year.

She has spent her entire life being encouraged to form close bonds with her paternal family, and she has done just that. She loves them, and they are important relationships for her (evidenced by the fact she in and out of their houses weekly). She exists independently of her sister, and her sister’s lack of paternal family hasn’t prevented, and shouldn’t prevent, her from actively participating in hers.

Expecting her to ‘take a stand’ for her nearly adult sister now will not teach her ‘loyalty’, it will only cement resentment (which even OP acknowledges, and given that she knows her daughter she’s unlikely to be wrong) it which is hardly conducive to either a good sibling relationship or a mother - daughter one.

Her older sister is not their family in the way that she is. That isn’t her fault, any more than it is the in laws fault. DD1’s lack of paternal family is the fault of her paternal family alone, and is not something the younger daughter and her family should be expected to either provide to her, or pay for.

You are quite literally prioritising the extended family here, over and above the nuclear family - and there lies the issue.

The extended family are not dd2’s primary family, that is made up of her parents and her sister. Her loyalty is to them, as it should be. They are the closest family members she has.

The division and difficulty is SOLELY being caused by dh’s family, we suspect the MIL but it could be all of them, they have chosen deliberately to create pain, damage and suffering to a child, a child that has been part of their family for decades.

Dh tried to reason with them, but he got nowhere. This is not an innocent mistake but a co ordinated and engineered deliberate plan to hurt dd2’s sister.

I ask you what kind of sister would she be to stand by and allow this harm for a SECOND time? What kind of family is this if they are so keen to cause such terrible pain to a child? Surely dh himself at this point withdraws his support of dd2’s wedding attendance, and says enough is bloody enough, we will not stand for this. He does have a spine in there somewhere I am sure…

Not only will this validate dd1’s feelings and help her feel loved, supported and valued as she should. Thereby strengthening the family relationships by extension.

It also draws a line in the sand to dh’s extended family about the kind of treatment they will and will not accept as a family unit.

It is just a wedding, no one is suggesting dd2 cuts them all off (although it wouldn’t be a terrible idea if she did) but in order to avoid this snowballing and totally wrecking op’s family unit, everyone must stand up to this bullying and ostracism as a united front, it’s the only way.

MeridianB · 28/04/2025 15:06

It also draws a line in the sand to dh’s extended family about the kind of treatment they will and will not accept as a family unit.

Yes. Because it's clear that it won't end with DD2 going to wedding number two. I suspect the ante will be upped - more solo time and events with 'real family' etc.

Gumsnvine · 28/04/2025 15:11

nomas · 26/04/2025 16:34

I agree. If younger one wants to go, let her.

I think if you stop the younger one from going, it will create resentment. And it’s not her fault.

But don’t facilitate it, DH should buy the dress etc.

Yes, I agree too- the younger one will be 18 eventually and then she will probably go out and choose to attend every single event her sister isn’t invited to if she is stopped from doing it now.

If you want her to have that loyalty and consideration for her sister it’s not something that can be forced . If you do, it’ll backfire.

You just need to hope eventually she’ll take a stance if it’s causing issues OR if she offers not to go the older one will be gracious and say it’s fine they’re your bio family go ahead, it sucks for me but I don’t want you to miss out. I think they both need to be thinking of each other but she’s far too old to be stopped from going to her relatives events IMO.

InterIgnis · 28/04/2025 15:14

Feelingmuchbetter · 28/04/2025 14:45

You are quite literally prioritising the extended family here, over and above the nuclear family - and there lies the issue.

The extended family are not dd2’s primary family, that is made up of her parents and her sister. Her loyalty is to them, as it should be. They are the closest family members she has.

The division and difficulty is SOLELY being caused by dh’s family, we suspect the MIL but it could be all of them, they have chosen deliberately to create pain, damage and suffering to a child, a child that has been part of their family for decades.

Dh tried to reason with them, but he got nowhere. This is not an innocent mistake but a co ordinated and engineered deliberate plan to hurt dd2’s sister.

I ask you what kind of sister would she be to stand by and allow this harm for a SECOND time? What kind of family is this if they are so keen to cause such terrible pain to a child? Surely dh himself at this point withdraws his support of dd2’s wedding attendance, and says enough is bloody enough, we will not stand for this. He does have a spine in there somewhere I am sure…

Not only will this validate dd1’s feelings and help her feel loved, supported and valued as she should. Thereby strengthening the family relationships by extension.

It also draws a line in the sand to dh’s extended family about the kind of treatment they will and will not accept as a family unit.

It is just a wedding, no one is suggesting dd2 cuts them all off (although it wouldn’t be a terrible idea if she did) but in order to avoid this snowballing and totally wrecking op’s family unit, everyone must stand up to this bullying and ostracism as a united front, it’s the only way.

Edited

The division was created when OP had two children with two men whose families would not offer their respective relatives the same. Trying to pretend that they are the same, and trying to force others into supporting that narrative does no one any favors.

I don’t hold the nuclear family to be ‘most important’, no. Family dynamics and nuanced and complex, particularly with blended families, and sweeping absolutist statements that don’t reflect that are rarely helpful to the individuals that make up those families.

Op’s youngest has been raised to be close to her paternal family, with her father at least actively encouraging it. Like it or not, her relationships with them are important to her, and she should not be expected to choose between her extended family and the one she lives with. It is not her fault that her sister does not have the same, and it is not her responsibility to give up her own for her sister. Harming her under the guise of ‘protecting her sister’, no matter how much you try and spin it into a positive for her, will not make anything for better, for her sister or anyone involved. Again, she is a person independent of her sister, with her own thoughts and feelings, wants and needs. Her sister is not the main character her life must revolve around.

She has been raised with this dynamic being absolutely normal to her. She knows, as her sister does, that her paternal family is not her sister’s and has no problem with it. She’s not going to suddenly change her mind because her mother wants her to now.

There is no reason for this wedding to wreck the family unit, any more than the last one did, or any more than the youngest being in and out of her grandparents house weekly, when her sister has little to no relationship with them, does. As if preventing her from going (if OP even could prevent a determined 14 year old from attending, especially when she has the support of her father) wouldn’t do the same amount of, if not more, damage that you envision her going would.

Gumsnvine · 28/04/2025 15:18

good Point @InterIgnis unfortunately people don’t think of these things when they create blended families. It doesn’t always work out like how you want it to.

My mum always wanted another child but didn’t partly because she didn’t want one set of kids getting treated differently by stepdad /in-laws.

Personally if that was my family I’d invite them all but people are different.

Itiswhysofew · 28/04/2025 15:21

It's a real pity it's happening again. He could've been more of an individual in his actions and welcomed DD. Never mind.

Let DD know that there are lots of us who wouldn't behave in that way.

Notonthestairs · 28/04/2025 15:33

Well, at the time of typing 80% plus have voted to thread indicate that they think the limited invitation was unreasonable.

That might be out of kindness for the uncle or simply because inviting 3 out of 4 family members would seem an odd line to draw.

Either way the majority of people wouldn't choose to exclude in these circumstances.

NotSafeInTaxis · 28/04/2025 15:46

Notonthestairs · 28/04/2025 15:33

Well, at the time of typing 80% plus have voted to thread indicate that they think the limited invitation was unreasonable.

That might be out of kindness for the uncle or simply because inviting 3 out of 4 family members would seem an odd line to draw.

Either way the majority of people wouldn't choose to exclude in these circumstances.

You can think the invite was unreasonable and still think the younger child can go if they want to.

I would invite them all, I don't think it was ok to exclude them. I do however think that if the related child wants to go, she absolutely can go.