I have two step children. The boy is 13 and the girl is 8. So I know what your going thru. Recently the boy started argueing with me about everything and refused to do anything I told him. This was strange for him, because we usually get along. It also caused several arguements between my husband and me. Hubby and I sat down and discussed our parenting styles. And in this conversation, he informed me that he felt that I was taking on too much of the parenting role with his children. So, we have made subtle changes over the last couple of weekends that the kids where with us. Mostly, me telling the kids "you need to ask your father." You know, make the effort to reinforce my husbands role as the parent. We tried alot of other things too, like talking to him "boy". This did help, he told me that he argues with me because he doesn't like my answeres and thinks if he continues to question me that I will eventually change my mind. I informed him of the disrespect he was showing me when he takes that course of action, and that I wouldn't tolerate it. I even talked to his mother. (She sounds to be alot like your daughter's mom.) MOM told me that he "boy" had been doing the same thing at home with her. Which helped, because I no longer felt that I was being isulated by him, or that he just hated me. I know some of it is hormones. and some of it is just a difference in rules between the two houses. But, things are slowly getting better. So advice is to communicate with your husband, and get his side too. Then adjust things that you can to better fit your weekends with your step daughter. And make a conscience effert to do so. And finally, you aren't alone, if she's doing it with you, she's probably doing it at home too, or at school, or with grandparents or somewhere. Keep trying and don't give up.