Just because roosters were raised together doesn't guarantee they will get along. It depends on the individuals involved.
A couple years ago, I discovered I had two cockerels in a batch of eight chicks. As soon as I figured out they were boys, around age four months, I separated them from the girls. They had their own coop and their own pen which had one common fence with the girls' pen.
By age six months, the two boys began to have fights in their coop. So I partitioned the coop with poultry wire so each boy had his own side with his own perch. During the day, I let one free-range while the other remained penned. Even still, they continued to have vicious fights through the chicken wire partition in the coop. I hung a curtain over the partition so they couldn't see each other. But during the day, the one out free-ranging would spend most of his time challenging the one inside the pen. Neither roo had access to the hens.
Finally, the problem was "solved" unhappily by the outside roo on a certain day getting killed by dogs who were visiting when their owner neglected to keep them controlled.
You run a very real risk that one or more of your roos will take a dislike to each other, and no matter what you do, you aren't going to be able to change their minds. My advice would be to re-home all roosters you don't really want. If they decide they need to fight, you end up with serious injuries to deal with.
