Keep an eye on the reintroducing. Someone here lost there's after the second time around. What I do is give the picked on hen special treats (trying to make them strong). Also make sure there are no other stresses, treat for worms, lice, mites, add little touches to make their pen more interesting. Make the coop as comfy as possible. Oh, you know what someone said here is give them a little protein because it helps stop the picking. I feed them crumbled hard boiled eggs, put a little extra calcium or oyster shell in there plus some vitamin supplements (you know, the Poly Vi Sol without the Iron). Try that a couple times a week until everyone settles in. You know I really think it worked for me. It took several weeks but now they all get along. Also let them free range because it's a great 'socializer.' If everyone is healthy and happy, they will all free range together.