I have 16 nest boxes and the hens all want to use the same one. And apparently they all have to lay at the same time. And let me tell you those gals get down and dirty. I've seen one hen pull another out by the comb. Kicking and screaming the entire way. I put meanie in the time-out area located beneath the nest boxes. It is simply a fenced off area set up to keep a hen and her babies in a safe area yet allow them to be seen by the flock. After a few days the flock dynamics changed enough so she wasn't so aggressive. On another occasion I put a pair of pinless peepers on a especially bossy hen and that cured her. Normally, I let the girls sort out their own problems but when I have one drawing blood I take action. And if the aggressive hen does not improve she goes to the bachelor pen where she is eventually rehomed for food purposes.