I would really encourage you to get Rosalind Wiseman's book Queen Bees and Wannabes. While your dd is only 9, mean girl behaviour can emerge as early as pre-school, and imo the book can be really helpful in identifying it and giving a girl tools to deal with it. I also think it is appropriate to talk proactively about the marketing directed at young girls and why her friends are buying into what is "cool" and what your family values are in this realm. If you just google tween marketing you will come up with some stuff that applies. Sorry your dd is dealing with it. My dd10 still plays with her AG dolls even though most of her friends do not and has not yet asked about Santa, but I think this is the year it is time to tell her. Good luck.
