Are they fighting over the male? Is the new female ready to have a litter as well? I think there may be jealousy issues if both are in heat, or the new one senses a difference in the older female. Is the fighting initiated only by the newer female?
Perhaps another male may satisfy the situation? Or if the newer female gets in heat and has a litter, that may possibly help? Just some suggestions I could think of, I'm sure some breeders may have more insight into this matter, welcome aboard blyorkie!
