I am looking for some advice on increased aggression between rats in my mischief and what I can do to help the situation. Thanks in advance t any one who can help. We have 7 female rats the oldest are 2 years old and the youngest are 1.3 years. We did have 8 but unfortunately we lost one of our girls due to a PT tumor last month, her name was Dobby and she was high up in the hierarchy and the biggest girl but seemed not to be the alpha. Our Alpha seems to be one of the bigger girls and the oldest, her name is River. Until recently, everything has been fine within the cage - the were play fights and small scuffles as dynamic changed now and then with the girl sometimes challenging others statues. Our introductions when we added to the group went well and we followed the carrier method. We haven't added to our mischief in 1 year aswell so there has been no new arrivals coming in. I am concerned as recently River has been having wounds on her back and she is being a lot more "standoffish" to the others seemingly. This started a little bit before Dobby died and has seemed to intensified after. It has been hard to see who has been giving her the wounds as these kind of fights seem to happen when I am not there. As said, they have gotten worse since we lost Dobby and I have wondered about whether this has been a reaction to the changes in their hierarchy due to that and he fact that River is getting older and a bit slower the others are challenging her more. There are a lot more non play fight scuffles happening recently and we have notice that one of the younger girls Beau (she has always been over confident and had what we called a sassy attitude almost but she is very small) has started having wounds on her. These are in multiple places at the top of her tail on her butt, on the side of her hip and on her front paw. We are not too sure who is fighting with who but I am assuming it is Beau and River. I'm not too sure what to do as this has been going on a bit longer than I am happy with to just continue keeping an eye on it. I'm not sure if I need to separate them, perhaps retry the carrier method introductions or perhaps see if I can adopt a neutered male into the group as an alpha to kid of calm that dynamic down. Any help would be appreciated. As said River is getting older and slower and I am worried about her getting seriously hurt or stressed fro all the challenging (she puffs up a lot now too). And Beau is much smaller than the rest of the girls and therefore I am worried about her getting seriously hurt too. Note: all of the girls show no aggression towards humans.