I have 4 rats. 2 older between 1 year and 6 mos and 1 and 8 mos. About 4 month ago I added 2 younger rats which were about 1 and a half months old when I got them. I did introductions and everything well very they had dominance scuffles but nothing out of the ordinary. Recently I have noticed that my older rats have bite marks on them and my younger ones do not. They have obviously gotten into fights when I’m not home and I don’t know what to do I have separated the older ones temporarily but am afraid to reintroduce them. I’m not sure what do do next. Please help!