a. you have too many roosters.I have 6 roosters. 1 got injured somehow before bed one night. Really bad limp, but no visible issues. Decided to separate him for the night. The next morning I put him inside the coop in a corner. Another rooster seen that and went right in to show his dominance. I kept him isolated a few days until he was a little better. I have heard the time to re-introduce chickens is at night. I tried that, and didn't seem to have as many issues as far as fighting.
b. it's virtually impossible to introduce, or reintroduce mature roosters together.
Hens go broody when you don’t want them to… and won’t go broody when you do. 