Help with my 2 dogs fighting.?

I would say dominance dominance dominance! Or jealously. I have a Father Son combo and they fight like anything due to jealously and it is always the son who starts it. His the same as your dogs he wouldnt hurt a fly, wouldnt hurt anyone or anything but the minute you are paying more attention to the Father, the son comes up yapping at his face (just like they would to a leader dog) licking his face and carrying on and the minute he hurts the Father in anyway all hell breaks lose and its game on. The minute they stop, the Son always licks the Fathers face and rubs against him as if to say 'Thankyou' when he almost got his throat ripped out.

There is nothing we can do, the minute we think they are going to fight we just get up and walk away. If you call them and carry on it only provokes them more. I think what's working with us is the walking away method, the minute we see that look in the Son's eyes we are up and out of the backyard or out of the way ASAP and because his not getting any attention he backs off and wonders where we are and things are starting to settle down, you can actually be around both of them longer than 10mins without them going eachother.

Your problem could also be the amount of dogs that have come in. He thinks that he has his family down packed everything is cool you get along fine than out of no where he has to compete with the new dog and no longer has that alpha dog strong connection and they can feel it. His probably trying to protect your Mum. Sit down and pound if into your Mum's head that she needs to start walking away from those situations when they are about to arise, its more than the least she can do.

Some people even use the confrontation approach. Have the 2 dogs on the lead and have the Pitbull with your Mum (either have your Mum controlling him or have a strong person who can control him there) and introduce the aggressive one slowly into the situation the minute he starts getting hyped up, tell him 'No' and turn around and walk in the other direction. Wait until he cools down abit, than try it again. If it's really bad it may take awhile for the agressor to register 'If i do this growling snarling business, i cant get near Mum, but when i stop, i get near her'. So keep doing it but don't let your Mum make eyecontact with the aggressor. When the aggressor finally settles down and is able to be in the same company as Pit and Mum praise him reward him 'Good boy!' looks of pats etc. Sometimes this can be a really affective way of over coming jealously and dominance issues between dogs. Other times it just doesnt sink in and you just have to hotleg it in those situations.

Another option is to teach our dog the 'Whistle Reward' idea. Train the aggressor separately. Get a whistle, blow the whistle and when he does the 'Huh?' face. Say 'good boy!' and reward him. Keep practicing it with him infront of you so he gets the 'whistle, reward' idea in his head. Than let him wonder around randomly than blow the whistle, tell him to come, sit and reward him. Keep doing this until he nails it. Than in situation like aggression, you blow a whistle and he automatically snaps out of it and looks for the whistle for a treat. Once again this doesnt always work (its mainly used for recall in hunting or when your dog is out running around and you want it back in the house) but it might work.

Other than that i have no idea, they're just a few options that i've seen become affective in situations. There are probably people here that will tell you exactly what your problem is, but i just thought id put my 2cents in!