She is in school right? any strange behaviors would have been reported to her parents and it's up to them to follow up. Many parents don't bother and many schools don't bother to find out if follow up was done. She sounds, by what you have said, that she needs family therapy with her parents and you. and so do you, and so do her parents! That's all I can say! She is acting out the dysfunction that is already there. Ask for family therapy and let us know how that goes. this is pretty serious because it is impacting your life extremely.