DD (14) has recently become close to a girl "A" (15) whom she's known since nursery but has never been particular friends with Her Mum and I are already good friends so it's a nice development in that we know each so well and can be laid-back about sleepovers, carpooling, etc. now the girls want to hang out a lot.
The only problem is that "A" has a history of telling lies to her Mum about where she's going/who she's with and last week, she got DD to go along with it. 
A group of friends was supposed to be going to a local restaurant for a birthday celebration (across the street from her house) but she actually got an older friend to drive them into town to a different restaurant. Of course, she got found out when she posted a photo on Instagram!
I was slightly surprised that the Mum allowed them to eat out unaccompanied in the evening, but I suppose they know the local restaurant really well. Anyway, her Mum was very upset as this is yet another instance of telling lies and I wasn't pleased with DD either.
DD and I had a talk about safety and how I was shocked that she'd lied to me. I think she got the message that I always need to know where she is.
How do I handle this friendship going forward? "A" isn't horrible, but she seems mixed up (parents went through a nasty divorce and she gets conflicting messages from them) and tbh I don't think she has much common sense. She really likes me apparently, thinks I'm nice and easy to talk to. But, she seems to seek out trouble and although DD is a strong personality (not easily led), she might go along with things if she thinks it'll be fun. I don't trust "A".
Ugh, I now wish they hadn't become close friends!