Firstly

I have a friend who was in a similar situation as you last year with her Dd but unfortunatley it didnt work out well sorry to say, but they left it too late and admit now that they should have sort out some help earlier.
I think she probably needs professional help, maybe a counseller or someone to find out what is going on as sometimes it is a cry for help in one way or another.. Im not aware of the full story, does she sell the items? Is she doing it for the money or just because she can?
Sorry i am not much help, i hope things improve for you, teenagers can do your head in.