I have 2 males and 2 females. Tessie, Hobbes, and Calvin are close in age. I got Sassy later and until we got her spayed she would attack Tessie, but not as violent as your females. Tessie was too laid back to bother with the efffort. I would seperate Sassy in the laundry room when she went into heat at an early age. They are all spayed and neutered now and it has made for a better Yorkie home, Sassy still tries to boss everyone and they usually let her. She is the baby brat of the house.
