Wait, you said you had 2 males and 2 females in there? Ok, no no no no, separate the male that is not the father, and the female that is not the mother, even when neutered 2 males can fight, and at least 1 won't make it to 15 years, but adding 2 females for breeding and 1 male unneutered is huge no-no. Even sometimes females that aren't related will eat each others joeys, please separate them immediately and do some more research before trying to breed again! I don't recommend breeding again, they could kill their joeys! How big is the cage? Show a picture? :(