My friend has two outdoor barn cats. Mama (spayed) and her son. Mama is very dominate. My friend would like to bring in one or two more barn cats for mice control. She is wondering if bringing a spayed female or two neutered males would be a better idea. Mama chased her son off. she is quite mean to him. He is basically feral, because of her behavior. Do you think she will accept another cat. Also how to introduce them ? recommendations please