I hope this is the right place to post this; if not, I'm sorry. 4 out of my 7 hens have taken to attacking one of the more submissive ones, Nina. Nina was one of the first hens we got, so I've had her over two years. This only started within the last couple weeks. If Nina goes within sight of the flock, one of the bullies will chase her down and pounce, pecking at her head. Her head has a bald spot now and her comb is torn up. Blue Kote did not deter them. I know chickens have an important pecking order, but even Svenia, the undisputed boss, has never been this violent. We tried putting two of the bullies in solitary for a few days, but as soon as they got out, they went straight for her. Nina is currently living outside but separated. She's very unhappy (though still laying and eating/drinking normally). She is the sweetest of the hens and a reliable egg layer to boot, so is there anything I can do to get her back into the flock safely?