About a week ago, I had the same problem. One broody buff brama hen amongst 4 others. I could tell they were fighting over the nest box - lots of feathers. I moved the hen and 6 eggs into another small coop and she took to the new nest just fine. She actually looks happy, not having to fight...
I learned this like everyone else - the hard way. Pay careful attention to the placement of your in-coop waterer. In my first two coops, I put their waterer a ways from the (people) access door. This necessitated either entering the coop and getting my boots all dirty or practically standing...