Because this involves aggression I suggest you consult a behavior-training specialist; you need to totally revamp your training methods, this is not a one-thing quick fix situation. We have a member whose name is scootiebootie who offers in dept training and special discounts for YT members. Here's her page.
http://www.yorkietalk.com/forums/mem...tiebootie.html. Since you have a young daughter and there has been biting, I suggest you contact her, or another professional before something serious happens. Let me just say, that behavior training is very valuable education, and the concepts can help with raising skin kids as well as our fur babies