When children are being attacked, I think the time is past for behavior modifications. It’s not worth the risk, the kids are more important than any chicken. Getting rid of this bully will bring a sigh of relief to everyone, and the kids can enjoy chicken keeping again.
Your kids don’t need this, sell her. We have poultry swaps here. You could look into swaps in your area, use Craigslist or other online forums. Good luck, keep us updated….