I wish I could help you Kas but all three of my male cats get along. There are times when they will fight like siblings or when one of them wants to play and the other one doesn't. I have two litterboxes but they usually only use one of them. They also have plenty of toys and two big scratching posts as you can see from the picture below. If Sunny isn't neutured that would be the first thing that I would do. It will calm him down and he shouldn't be as territorial either. Good luck.