Daughters friend

[Iwasatglastothisyear]

Daughter (14) made friends with a girl online, Emily (15) about 18 months ago (no stranger danger comments please because I police her social media like a hawk)
We went to an event and Emily was there so they got to meet in rl, hit it off and became really close.
She has been to stay with us a few times (mum put her on the train for a 4 hour journey, which I found really strange but I'll save that for another time) and the two of them have always got on really well.
Anyway, Emily has started posting things on her social media lately that have been questionable. Almost begging for attention and coming across as someone she isn't. Arranging to meet people she doesn't know, using foul language and just posting really needy things. Her and my daughter have drifted over the last few weeks and have barely spoke to each other as my daughter doesn't like what this girl has become. I've tried to encourage her to talk to Emily to find out what's going on but she's reluctant to do so. I've also tried to talk to the girl but haven't really had much luck.

Should I just accept the fact that these girls have moved on from this friendship or should I contact the mum to see if she's aware that there's a problem? She doesn't have social media so is most likely unaware of what's being posted but I don't really know her either (which is strange as her daughter has stayed here, I know)
We've only physically had one phone conversation and a few texts and that's it.
I'm not sure what to do in the situation where part of me is a bit concerned about how dramatically this girl has changed. I know kids go through the phase of giving it all that (I have an older son and daughter myself) but I'd welcome some advice please.

It is a tricky one, but personally, I would definitely drop the mum a quick text or phone call... not so much about the bad language etc. (as like you say, this isn't exactly uncommon for teenagers to go though periods like that) but the arranging to meet up with people she doesn't know would be what would concern me (but then I work in safeguarding and so am immediately pessimistic!)... at least then you know you've passed it on to the parent and what they choose to do with that information is up to them... if that makes sense? Usually if you have a niggling worry about something then something usually isn't right, especially if it's a dramatic change in behaviour.

It would be so much easier if I knew the mum

Definitely talk to the mum.

Assess what you can see, decide if there is seriously concerning stuff or just big talk.

But don’t put it on your daughter to protect this other girl. If she doesn’t want to be friends with her it’s unfair IMO to push it - especially as she may be scared of the kind of things her erstwhile friend is saying and doing.

I suggested (gently) to my daughter that I speak to the mum and she's been very much against that, as she's worried that there will be some kind of comeback on her.
One of the things we've noticed Emily doing is calling out other kids online, almost bullying them and then playing it down, saying she was joking.
I think DD is worried that's what will happen to her if I talk to the mum but in the same breath I'm worried there may be a real problem.
I'm feel as if I'm torn between helping this girl and protecting my own child.

I genuinely hate what social media is doing to our kids.

Can you determine which school Emily goes to and contact them rather than her mother.

She's just finished school unfortunately (August birthday, when she'll turn 16) or that would've been a good option

This might be irresponsible but honestly I’d just leave it. If this was a rl rather than online friendship you wouldn’t have a clue how a 14 year old girl 4 hours away from you was behaving. It’s not really your problem and it’s definitely not your daughter’s! I think tbh this could really upset your DD if not careful. There’s not much either of you can do, but I feel like if the friend does turn out to have problems/ get into trouble you’ll feel responsible. You’re an adult and you sound worried enough but imagine how that might impact your DD ?

One of today's posts says "I wish I was dead"
I don't really think that's normal behaviour but a cry for attention.
I'm finding it hard to gauge though as to if this is something teenage girls do, as DD is a bit of a nerd and always happy to talk to either myself or her older sister about her problems.