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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

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:
LAMPS1 · 14/02/2025 00:21

What a sad and difficult situation for you all.

I think that, as soon as DP returns home, you should go back to your own home and allow him to talk to his DD and get to the bottom of it over a period of time.
It’s possible that your SD doesn’t want to share her home (or share you) with your DSis. So she is testing the boundaries. She wants you to believe her so that she feels loved rather than rejected.
Either girl could be fighting to hold her position with you and needing to feel your allegiance. I do think that SD may have stronger need to do that.

It would be better if you stayed out of it and hosted your DSis as normal in your own home, until it has all been resolved amicably.
It will be easier for the truth to emerge with you having temporarily moved out.

Happyhippos123 · 14/02/2025 00:21

Both girls are very lucky to have you in their lives, you sound very caring and sensible, you've really stepped up for both of them.

I hope it gets sorted, and that you aren't forced to choose between both girls.

RebelStarChild · 14/02/2025 00:25

PandaTime · 14/02/2025 00:15

Equally if the sister was going to send texts but pretend SD sent them to herself, she could only do that when SD would have the opportunity...

Someone is either very cunning or immature and desperate.

For the sister to have sent the text and pretend the girl sent them to herself is a bit much.

The OP is the only one to suggest that the SD sent them, the sister would have suggested this when asked if that was her plan all along.

The hysterical reaction from the SD along with wanting the sister banned but not told why is suspicious enough, but if the texts were sent in the middle of night with no provocation or specific incident between them that day, then I would say the SD is the most likely culprit with a very obvious motive.

LilacLilias · 14/02/2025 00:29

Yes I think SD did it, mainly because OP knows these girls very well and probably has the right instinct about it.

However, the problem is kind of how to deal with it when you don't have proof either way so you could be wrong.

KrisAkabusi · 14/02/2025 00:29

ReginaTucker · 14/02/2025 00:16

But she’s not parent to either of them so you can’t really judge her parenting!!

If you're a stepmother, you're a parent. It's not a popular opinion on here but that doesn't resolve you of responsibilities.

Kingsransom · 14/02/2025 00:32

You can't know either way, so kicking her out of her home would likely cause serious problems in your relationship. Whose house is it?

LilacLilias · 14/02/2025 00:33

KrisAkabusi · 14/02/2025 00:29

If you're a stepmother, you're a parent. It's not a popular opinion on here but that doesn't resolve you of responsibilities.

It's not the same thing. Some step parents take on a full parenting role, others don't. Quite a lot of step-parenting literature suggests that the best thing is when stepmothers take the "fun auntie" role. Having a SD doesn't automatically mean OP should be parenting her in the same way her dad should be.

Step parents do NOT have parental responsibility, legally or otherwise.

PandaTime · 14/02/2025 00:43

RebelStarChild · 14/02/2025 00:25

For the sister to have sent the text and pretend the girl sent them to herself is a bit much.

The OP is the only one to suggest that the SD sent them, the sister would have suggested this when asked if that was her plan all along.

The hysterical reaction from the SD along with wanting the sister banned but not told why is suspicious enough, but if the texts were sent in the middle of night with no provocation or specific incident between them that day, then I would say the SD is the most likely culprit with a very obvious motive.

My point is it is impossible to prove without a confession. And it isn't necessary because that isn't the real issue. Whichever child did this (which is most likely SD) they did it because they are unhappy. That is the real issue here.

latetothefisting · 14/02/2025 00:43

Kingsransom · 14/02/2025 00:32

You can't know either way, so kicking her out of her home would likely cause serious problems in your relationship. Whose house is it?

maybe take a second to read OP's posts, where she's answered this?

Isittimeformynapyet · 14/02/2025 01:36

I don't know if anyone else has suggested this, but you could tell your sister what was in the texts but include something that wasn't.

You never know, she might blurt out "I did NOT say that!"

user1492757084 · 14/02/2025 02:27

Believe your sister but also don't say that you do not believe your SD, in that they came to her phone.
Tell them both that the whole thing has upset you and that you have no more time for the incident.
Insist to your sister that if she did send the messages, she is to stop and never again be so mean.

Insist to SD that you do not believe that your sister sent such mean messages and perhaps she has another friend who was playing a very mean trick. Can she think of anyone who might do that?

Call a truce and shake hands and all go out to a movies or eat ice-cream.

Be on the watch for similar behaviour.
SD could be feeling jealous, vulnerable and unsettled.

WiddlinDiddlin · 14/02/2025 03:58

Assuming you do not manage to trip up DS into revealing she does in fact know what some of the messages said, which, if she did not send them and they were deleted before she could see them, she should not know (and I don't recommend deliberately trying to trip her up!)...

As you cannot tell who is lying...

Tell them both...

DS is always welcome in the house it is still her home too..
DSD is also welcome in the house, it is still her home also.

These two factors are non-negotiable.

Phones are now to be put into a locked box at Xpm each night, which you have.

That way, no one can send anyone nasty messages.
No one can be accused of sending nasty messages.

Neither has any grounds for objection to this, as it protects them both. (So if either DO have an objection to it, thats a good indicator as to who it really was!).

Then move on - draw a line under it. But examine why, potentially, DSD is trying to push DS out, is she feeling insecure/anxious, theres an underlying issue there if that is the case. And of course it could be DS trying to paint DSD in a bad light just as equally... But that is something to observe and evaluate, I don't see that punishments when you cannot be certain who did what, will achieve a positive result.

thatringoffire · 14/02/2025 04:11

Check both phones.

Your step daughter can obviously change any phone number to your sister's name to show her name next to a message. You'll need to physically go in and check the number!

Equally your sister will no doubt deny things too.

Good luck getting to the bottom of it!

Mummyoflittledragon · 14/02/2025 04:11

in my experience tween girls can be particularly tricky and tend to tell a story to a slant that paints them in the best possible light. This isn’t to lie but because of the process of brain rewiring. They lack empathy at this stage as well and things can become very brutal and savage. If this situation isn’t handled with a lot of love and care for both girls, it could permanently sever their relationship.

I wouldn’t be automatically believing your sister. Tween girls do and say the most stupid things and lack the ability to see consequences of their actions. My dd was on the receiving end of some brutal behaviour at this age as well as nasty texts. And I saw dd saying things so out of character that she just wouldn’t have said a year or so before. If a girl of this age isn’t being heavily supported they can become rather feral.

I also think in a way it doesn’t matter who sent those messages. It’s some form of cry for help. Keeping the girls apart is the right thing and not having your dsis in the house is what your dsd wants for the time being. So caring for her when her dad isn’t home then sending her to her gps when you need to care for your dsis. I’d explain to both it isn’t a punishment for either. But to tend to each of the girls needs.

Once you have the girls 121, after a period of time, you may find that one of them reveals they lied. For now, it’s important to speak to both of them but I wouldn’t do it together. They need space from one another. They’re too vulnerable to be treated like warring siblings in a safe family unit imo. Things may be said in the heat of the moment that cannot be undone and you could quickly lose control of the situation. I would do it individually and be clear, you love them and there will be no consequence for telling the truth. You want to believe both of them. However, they aren’t both telling the truth. All you want is to be able to support them both as one of them, or perhaps even both of them, is very unhappy.

In my experience, my dd revealed a lot to me at this age just by holding a line of I love you, I won’t be cross, you can always tell me anything.

@AssassinsBlade made a really good point that this may be your dsd finding a way to tell you something she can’t tell you openly.

Either way, get an agreed PIN code on each of the girl’s phones. You can make a note of the pins on your phone so that you always have access to them. They don’t have to be complicated codes.

HelmholtzWatson · 14/02/2025 05:20

The fact that you are "99% sure I believe" your sister over your SD is quite revealing.

In reality there is a fairly equal chance they are lying, and I think the burden of proof is on your sister.

Also, have you kept your SD's phone and not your sisters? You should have taken both of them immediately until you figured out a way of getting to the bottom of it. One way might be to look at some of the activity metrics, such as battery life. If your SD stole the phone just to send messages, then battery drain would be minimal. If your sister had the phone, it would be likely she was doing lots of other stuff on the phone at the same time, and battery drain would be greater.

Justsayit123 · 14/02/2025 05:22

Add passwords to the phone as it means anyone could access them! If they have Apple Pay etc, that’s really risky.

ohyesherewego · 14/02/2025 05:39

If you still have SD phone why won't you text your sister "hi"

Hopefully sis would respond hi

Then from SDs phone " why did you send those text messages?"

Surely then however your sis replied would give you the answer you were after and you would know.

Sadsadworld · 14/02/2025 05:48

What is going on in general with each of them and with their relationship? Would it help to look more broadly at this? If you are right, is this a cry for help from SD, a way of telling you the things she's worried/embarrassed about?

SoNiceToComeHomeTo · 14/02/2025 05:49

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 agree. Things are not OK between these girls and one or both may be crying for help. Tread carefully. Sending abusive messages is serious and so is faking this scenario.

Glittertwins · 14/02/2025 05:57

To ensure it doesn't happen again, set up passwords / Face ID if possible on both phones and then remove both phones from an accessible place overnight.

LAMPS1 · 14/02/2025 06:11

As you cannot tell who is lying...
Tell them both...
DS is always welcome in the house it is still her home too..
DSD is also welcome in the house, it is still her home also.
These two factors are non-negotiable.

@WiddlinDiddlin
No I think this is very much the wrong thing to do and could make things much worse for both girls as it is incorrect.

It is in fact DSD’s house. Of course she’s welcome there, it goes without saying. She lives there with her father who has to work away a lot.
Whereas DSis is very much the guest in the house I believe. DSis is normally cared for in the OP’s own house at a separate address when she isn’t at her own home where she lives with her mum.

It’s very possible (though not certain) that with the presence of DSis staying in the house and feeling very comfortable there with her big sister looking after her, DSD has become so fearful of losing her security and control as well as her special bond with her SM, that she has felt driven to do this to secure her place. Who can blame her not to react. Did anybody ask her if it was ok with her for the DSis to come and spend days there. There’s a difference between actually living there and being a temporary guest there and this should be properly acknowledged.
OP says that the girls seemed friendly enough but who knows what was really going on in either of their minds as it appears they have both had such a lot to deal with already in their young lives. Security is lacking for both of them so care must be taken with the feelings of both girls.

Both girls need a lot of reassurance and it’s the DP’s basic responsibility to provide that for his DD when he gets home and finally understands the full facts and truth of what has gone wrong here.

MissJoGrant · 14/02/2025 06:13

MissUltraViolet · 13/02/2025 22:20

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

Yes, but some posters have suggested the name had been changed on the messages - ie SD had saved a different device's number as the other kid's name.

zerogrey · 14/02/2025 06:37

If they came from your sister's number then she obviously sent them. You need to check her phone regardless and stop making this more complicated than you have. Even if she has deleted them, the carrier will have evidence of it.

Check the bloody phone.

NoBodyIdRatherBe · 14/02/2025 06:44

If your SD sent them from your Sis phone why would she delete the messages? Surely she’d want the evidence to remain on the phone. It’s a difficult situation but you can’t really know who’s lying. Has either girl got form for dramatics/lies/manipulation etc?

dementedmummy · 14/02/2025 06:59

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.

Do you know there are apps which can spoof a number so it looks like it's coming from a particular number? Has SD fallen out or had friendship difficulties with her friends? Just wondering if a friend has done this to be nasty to SD and planted your sister as the villan? Also unless it's Snapchat, you will see that messages have been deleted on your sister's phone