If Pixie is an energetic puppy, part of the problem might be that she feels "trapped" when your daughter holds her. This happens with adults too, when a puppy would rather be free.
This is not to say that aggression is ever acceptable, but observe the interaction to see if this might be the root of the problem.
Even with my adult Yorkies, I believe one of the reasons they are so affectionate is that they know they are always free to leave my lap or my embrace when they choose.
I believe Yorkie puppies tend to be even more feisty because of all of the puppy energy. When Pixie acts up, I would tell her "settle down" or some other command. Teach your daughter to let Pixie leave her and to save holding for later when the puppy is calmer, tired out, ready to accept holding.
__________________ Kristin, Max and Teddy  |