Had 3 related presa girls that were fine...until the youngest got closer to a year, and started trying to climb the ladder. Thought the first fight was due to an illness of the oldest (alpha bitch), but the oldest wouldn't even be in the same room with her without getting hostile when she was better. The one stuck in the middle is the youngest's mom, who is about a year younger then the alpha, and the older two are cousins, and have never had a problem. However, shortly after starting in on the oldest, the youngest then tried to take on mom. Not wanting to waste money at the vet's, we just ended up separating them. We're used to it with the boys, so it was nothing new for us. That may be the final solution for you if you can't find a way around this. It would most likely end up needing to "put the fear of god" into the girls, but that would only be trustworthy if you were around.