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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

Original poster

To believe sis(12) over SD(11)?

335 replies

Bestofgoodluck · 13/02/2025 19:08

SD is 11, have been with her dad for 5 years, mum is not involved. DP has to go away often for work and I work from home so look after SD while he’s away. This is mostly been fine, she has the option of staying with grandparents but chooses to stay with me.

I also have a 12 year old sister, our mum has quite a few problems and as I am older, she has stayed with me on and off since she was a baby.

They are completely different but have settled into a friendly but probably not friends relationship and there has never any major problems between them. I have been looking after both a them for about a week. They go to different schools and do different activities so don’t see each other that much but when we’ve been together everything has been fine and they both have seemed happy.

Sister went back to our mums today and SD came to me in tears and showed me some extremely nasty and embarrassing messages sent from my sister to her last night, I comforted her and said I would talk to my sister, she cried for me not to and said just not to make her see her anymore.
Sister said she had no idea what I was talking about and that there were no messages on her phone, was asking what they said and why she would do that, I’m 99% sure I believe her. I was already thinking the wording and content of the messages didn’t seem like things my sister would say and more likely that SD sent them to her self.

I feel completely torn between the two of them and can’t see how I can sort this between them or know who is telling the truth.

AIBU to choose my sister over my stepdaughter? And to say SD has to go to her grandparents if DP is away and my sister wants to stay with me?

OP posts:
Nowthesaidmother · 13/02/2025 21:56

This is a cry for help from your dad assuming she is the one who's lying.
So you need to find out why she doesn't want your D's to stay any longer.

If she's not lying, and it's your ds, you need to understand why she's being so mean.

The best way to do this imo is take pressure off them about lying. Don't make a big deal about who's the liar, who's lying etc but give them a way to communicate what they really need to communicate.

LilacLilias · 13/02/2025 21:57

I might be being paranoid but I think if they're going to be getting silly with phones you might want to tighten up rules with them and ways to make sure they don't get into each others hands. If one is being naughty and sending rude messages on the other's phone they could potentially cause all kind of trouble - hurtful messages to friends etc

ThejoyofNC · 13/02/2025 22:02

The fact that she's pushing for your sister to no longer be allowed to stay there makes it pretty obvious to me (from the limited info) that that's her plan and has cooked up this story to try and make that happen.

Not a chance I'd be told by a child that my sister couldn't stay in my home, nasty messages or not.

DojaPhat · 13/02/2025 22:02

I'm not sure if this has been covered but what sort of phone does your sister have that someone other than her could ostensibly open it, send a ream of texts then delete the evidence, place the phone neatly back where she took it without creaking so much as a door handle and breathing so quietly a mouse couldn't hear?

ThejoyofNC · 13/02/2025 22:07

DojaPhat · 13/02/2025 22:02

I'm not sure if this has been covered but what sort of phone does your sister have that someone other than her could ostensibly open it, send a ream of texts then delete the evidence, place the phone neatly back where she took it without creaking so much as a door handle and breathing so quietly a mouse couldn't hear?

Plenty of ways to do this without any of the above.

Photoshop
Fake message apps
Saving another device (iPad?) as sister's name
Getting a friend to send them and saving them as sister's name

LilacLilias · 13/02/2025 22:09

As pp said it is also possibly suspicious if she was on her phone all day but only appeared to "read" the msgs after sister left. But maybe she wasn't on her phone til then?

MissJoGrant · 13/02/2025 22:13

MissUltraViolet · 13/02/2025 19:27

It’s a little bit irrelevant. Whether SD sent them to herself in an attempt to frame your sister or your sister actually sent them, they do not have a friendly or happy relationship and the current set up isn’t working.

Whatever the truth if it, his incident does not mean their "set up isn't working". I think your anti-step bias might be showing.

PandaTime · 13/02/2025 22:15

Gosh that's a tricky one. The messages exist so they were definitely sent from one phone to the other. But I don't know how you could prove who sent them. It's one troubled girl's word against another troubled girl's. Personally, I would see this as communication. Someone is trying to tell you something. If it was SD who sent the messages, she is clearly trying to tell you that your sister being in her life and in her home so often makes her unhappy. You really shouldn't be this torn. Your sister's visits should not be at the expense of your SD. This is her home. Try shorter visits. A week is a long time to feel put out and uncomfortable in your own home.

Original poster
Bestofgoodluck · 13/02/2025 22:16

This all happened in DPs and SD’s home where I live 90% of the time but I do have my own place where my sister has always stayed before.
DP is away until next week, He agreed that SD could be lying but has asked her and she said no so can’t expect him to do anything else at the moment as she is so upset. He has also always made it clear that I’m not expected to look after his dd, I don’t want her to have to go to her grandparents, I do love her and enjoy looking after her but my sister doesn’t have an alternative safe space.

Honestly I’m finding it hard to be looking after SD and comfort her while believing she’s made up horrible lies trying to get rid of my sister.
I didn’t really consider why she would do this but obviously either way she’s really upset about something and needs support.

I agree the goal is to sort out the relationship between them and to continue the arrangement as we are.

OP posts:
MissJoGrant · 13/02/2025 22:18

Ask both kids phone providers for an itemised bill (costs about £2). You'll be able to see when texts were sent and from whose phone.

MissUltraViolet · 13/02/2025 22:18

MissJoGrant · 13/02/2025 22:13

Whatever the truth if it, his incident does not mean their "set up isn't working". I think your anti-step bias might be showing.

Show quote history

Well you’d be wrong. Anti-step bias is showing? You tried so hard to be clever and cool there. 😂

I am a step-daughter and step-sister and you’re talking nonsense.

ExercicenformedeZ · 13/02/2025 22:19

I'm really surprised at the voting, I think you are definitely being unreasonable and favouring your sister over your SD. You haven't given any concrete reason why you believe her over SD. I'm not sure what the answer is, but your posts do seem to paint the SD as the problem not your sister, which makes me feel bad for your SD. Just because your sister is your blood, doesn't mean that she is any better than your SD. How would you feel if your husband decided that your sister was definitely the problem and shouldn't be coming round?

Tiswa · 13/02/2025 22:19

Bestofgoodluck · 13/02/2025 22:16

This all happened in DPs and SD’s home where I live 90% of the time but I do have my own place where my sister has always stayed before.
DP is away until next week, He agreed that SD could be lying but has asked her and she said no so can’t expect him to do anything else at the moment as she is so upset. He has also always made it clear that I’m not expected to look after his dd, I don’t want her to have to go to her grandparents, I do love her and enjoy looking after her but my sister doesn’t have an alternative safe space.

Honestly I’m finding it hard to be looking after SD and comfort her while believing she’s made up horrible lies trying to get rid of my sister.
I didn’t really consider why she would do this but obviously either way she’s really upset about something and needs support.

I agree the goal is to sort out the relationship between them and to continue the arrangement as we are.

I think if you are you cannot be in your DPs and SD home thiugh when they aren’t

where are you the 10% of the time can your sister go there?

bexause if this isn’t fixable your sister can’t come into your SD home because that is her home. I think if you need to be there for your sister and your DP is away then yes grandparents makes sense

but not in their home

MissUltraViolet · 13/02/2025 22:20

MissJoGrant · 13/02/2025 22:18

Ask both kids phone providers for an itemised bill (costs about £2). You'll be able to see when texts were sent and from whose phone.

She knows all that already. An itemised bill can’t show you who sat there typing it.

StormingNorman · 13/02/2025 22:20

Bestofgoodluck · 13/02/2025 20:36

’m very cautious about actually accusing either of them, If I’m wrong then the one whose been wrongly accused is going to be very hurt.

SD is saying she doesn’t want my sister to be allowed to stay. I can’t tell my sister that she can’t come and stay with me if she needs and honestly even if I did think she sent them I wouldn’t want to do that.
I only look after my sister when she chooses to come and if I accuse her and she didn’t do it then she is just not going to want to come anymore.
So don’t know what option I have apart from saying to SD that if she doesn’t want to be around my sister and my sister wants to stay while her dad is away then she will have to go to her grandparents which until a couple of years ago was her only option when her dad worked away.

You can’t kick your SD out of her home to make way for a visitor.

Tiswa · 13/02/2025 22:21

And children don’t make up lies for a reason - this is on you, you haven’t managed this well and clearly there is some resentment - and I think perhaps having your sister in your SD soace isn’t working

UndermyShoeJoe · 13/02/2025 22:21

So this isn’t your home? It’s hers and her dads and now she has to share it with your sister child when you decide when they don’t like each other. Yeah no. If you want to watch sister you have her at your house and she goes to grandmas not she goes to grandmas and you have sister in her home.

ExercicenformedeZ · 13/02/2025 22:22

Bestofgoodluck · 13/02/2025 22:16

This all happened in DPs and SD’s home where I live 90% of the time but I do have my own place where my sister has always stayed before.
DP is away until next week, He agreed that SD could be lying but has asked her and she said no so can’t expect him to do anything else at the moment as she is so upset. He has also always made it clear that I’m not expected to look after his dd, I don’t want her to have to go to her grandparents, I do love her and enjoy looking after her but my sister doesn’t have an alternative safe space.

Honestly I’m finding it hard to be looking after SD and comfort her while believing she’s made up horrible lies trying to get rid of my sister.
I didn’t really consider why she would do this but obviously either way she’s really upset about something and needs support.

I agree the goal is to sort out the relationship between them and to continue the arrangement as we are.

What? Your partner ought to be sticking up for his daughter, the poor girl. Your sister's safe space or lack thereof is not her problem, if there is a problem between the girls, you need to keep your sister away. Even if this is a frame up, I'm not sure I blame your SD. You need to keep your sister in your place and stop expecting your SD to play happy families.

PandaTime · 13/02/2025 22:23

I agree the goal is to sort out the relationship between them and to continue the arrangement as we are.

I don't agree with this at all. You're treating your sister like a daughter, which makes this arrangement more like a blended family. Blended families have to work for everyone involved. One child's happiness shouldn't be at the expense of the other. This setup is not working. The solution isn't to force them to have a relationship. The solution is to unblend the family.

AnotherDayinTime · 13/02/2025 22:24

MissUltraViolet · 13/02/2025 19:27

It’s a little bit irrelevant. Whether SD sent them to herself in an attempt to frame your sister or your sister actually sent them, they do not have a friendly or happy relationship and the current set up isn’t working.

I would stick to my own blood here, console the step child ( of course), but if it is not easy to prove who sent what , both can be in the wrong.

Original poster
Bestofgoodluck · 13/02/2025 22:25

The content of the messages were picking on insecurities I know sd has, things that sis either also has or things wouldn’t even be on her radar.

There were also threats to tell all her friends embarrassing things, these embarrassing stories for sd wouldn’t be considered embarrassing for my sister and she doesn’t actually know any of her friends so don’t know how she would do this anyway.

OP posts:
Tiswa · 13/02/2025 22:27

You aren’t listening - those messages and things don’t come out of nothing.

if your sister needs you go to your place and then yes yiur SD goes to her grandparents but you cannot do it at her house

ExercicenformedeZ · 13/02/2025 22:27

AnotherDayinTime · 13/02/2025 22:24

I would stick to my own blood here, console the step child ( of course), but if it is not easy to prove who sent what , both can be in the wrong.

Show quote history

Yes, but then the father should also stick to his own blood, and tell OP that her sister isn't welcome in his home.

Anonforthis58 · 13/02/2025 22:27

Quite honestly, either girl could be lying so I’m not entirely sure why you’ve automatically taken your sisters side 🤷‍♀️
I would get them both together and chat things through with them, together.
Out of interest, how old are you OP?

UndermyShoeJoe · 13/02/2025 22:28

your not listening.

the child should not be kicked out of her home for your sister to stay. She shouldn’t be uncomfortable in her home.

If you want to watch your sister do it at your home. While she is at granny’s.

You don’t kick a child who’s already got only one involved parent out of their home to prioritise another persons child especially when you can take them to your own home.

Her home is her only safe space with her father after having an uninterested mum.

Your sister had her mum, even if not great and you. You and your sister are invading her space.