For not letting dd hang out with this girl

The more you try and ban her, the more your daughter will gravitate towards her.

I think you need to focus on behaviour rather than the person. Because the object is to raise your child to understand the difference between sensible choices and those that aren't, and to have the confidence to make them, not shield her from every child you fear may influence her. The second is almost impossible really, as not only can you not control who she is drawn to, you also have no more than a snapshot of any child with which to judge who the 'good' one's are.
So rather than ban the friendship, work on the rules for your DD. Leave her in no doubt what you expect her to do (stay in the library if she's agreed to, not disrupt classes, not post certain things on SM etc) why it's important, and what the consequences are if she doesn't comply. Then keep your eye on HER behaviour.

I agree - I'm really surprised, given all the media reportage about the dangers of social media, and moves to restrict social media to over 16s (in the UK, and already in Australia and other countries), that 12 year olds are still being given access to social media (even if restricted). The research shows that it leads to precisely this kind of subtle alienation/marginalization/anxieties that are starting up here.

I’d take your 12 year old child off social media personally.
full of bad influences on there

It's fairly common for parents to think that their own child is naive, quiet, and easily influenced, whilst it's just the other children who are a bit wayward.

It's usually a bit more balanced than that irl.

You also say that you have given in to her demands for something proven to be detrimental to someone as young as her because you don’t want her to be ‘alienated’ and yet are keen to alienate her from a person she describes as helping her to settle in and feel supported in the real world. If that’s not mixed messaging for her then I don’t know what is.

If you’re letting your 12-year-old have access to social media, then this one girl is likely to be the least of your problems. It’s particularly interesting that one of your concerns is that the friend ‘posts fairly depressing’ things on SM yet you are happy for your daughter to have access to an entire world of posts like this, especially as, in your own words, she’s ’easily influenced’…

I’ve been on the other side of this… I was that girl that other parents stopped their daughters hanging out with. Instead of being judged and isolated, what I really needed was some good influences in my life and for someone to actually ask if I was ok. I was suffering from abuse and neglect at the time. I’ve wished so many times that the parents of those other girls could have checked whether I was ok instead of ostracising me. It could have saved me from years of pain.

You sound way too controlling, OP. Your DD is 12 and you need to step back and let her choose her own friends now.
I think most parents don't always like the friends their kids choose, but it's their choice; unless they're involved in crime or something more extreme than what you have posted here.

You won't be able to stop her, but what you can is talk about choices always lead to consequences, good or bad, and to always think through decisions. Couple this with letting her blame you if she wants to get out of something she's not comfortable with, and she should be okay. I was always happy for my kids to use me as an excuse, and that they'd be rescued from non ideal situations if needed.

My daughter is in y11 she’s 16, she has been friends with a girl since y7 (aged 11) the girl is always in trouble talks back at teachers is gobby , misbehaves something awful , she has a dreadful home life , my daughter is quite well behaved and never speaks back unless something awful is said to her , I’ve never stopped this friendship my daughter knows how to act and behave and has never let her friends behaviour encourage her in fact my daughters behaviour has often encouraged this girls behaviour to revise for exams acts , and when my daughter was being terribly bullied guess who had her back ? . You need to stop trying to end this friendship you have no real reason yet to step in you will isolate your daughter

Awful.

OP, don't you think that the good side of this girl could outweigh the bad side? She has been kind and welcoming to your DD, to me that is more important than the bad things you have said. I'd rather a girl who is a little too mature than a girl who is unkind or mean.

Re not letting her be with her friend after school as you're not sure they'd actually stay at school, do you mean your DD isn't allowed to go out after school with her friends? Why not? Most 12 year olds are allowed to do this IMO.

You've damned this girl without actually knowing her at all. So what is she talks back to teachers! You don't know her background etc.

Encourage your DD to invite this lass (and other friends) round for tea/sleepover/whatever. Keep an open mind.

Listen to your daughter when she says this girl is helping her.

If you want to encourage your DD to keep secrets and distrust you carry on making judgements about her friends and communicating them to her.

What sort of content does she post on SM which worries you?

What do you mean by “talk back to teachers”. Is she rude or just different opinion and not worried about voicing them?

Your posts are not that clear to me.

The more you tell her not to be friends with the girl, the more she will double down on being friends with her.

Equip her with the skills, knowledge & confidence to make good choices regardless of her friendships.

No it isn't safe. Experts know this. Why else do you think there rule is 13 years old and probably moving up to 16.

I'd have no issue with my child being friends with a child like this but I wouldn't have them on social media. My son is 12 and isn't on it. Not alienated at all and has no interest in it

We had a birthday party for my son (now 13) last year and tbh all the girls were on sm and all the boys gaming. I’d also agree that if you push she’ll pull away more and think you should invite her over. My son had a friend we knew of as being older and tougher in personality and he’s surprised us in terms of both common sense and things we’ve caught him saying. A 12 yo isn’t quite at the stage where they have so much freedom to be able to hang around town yet so just keep a close eye but also don’t try to stop them being friends

I'd ignore everyone on here to be honest. If I could see my child being lead down the wrong path, I'd put a stop to it. Your job is to be her parent, not to let her do whatever she wants.

Many of us have been through the “everyone else has it” battles and still said no because it’s not what’s best for them. There are age limits (which are too low in my opinion) for a good reason. Australia is banning social media for under 16s for a good reason.

You don’t want your 12 year old susceptible to bad influences yet you allow her to be on social media (illegally). Make it make sense.

Why is your daughter on social media at 12?

You wont win this battle with how you are doing it.

Reinforce your own boundaries and expectations, promote other friendships and activities outside of school.