have two sister rats and dominance is decided. i think, well the bigger one usually wins the fights lol my other is a runt. the runt isn't as playful and squeals when the bigger one trys to roll her over, play, lick her. so she doesn't have a play buddy when im gone. ive tried toys and tunnels but she takes no interest she likes to wrestle, she always wrestles my hands its so adorable. they are 4 months old since october 15th. (rounded their birthday to two months before i bought them since they were two months) would it be wise to get another rat? if yes, should i get a younger rat or older? and if no, what should i do? ill still have to ask my parents and im sure they will say no because they weren't to happy about these two.