Update - Over the course of the last few days, I would let the chickens out in the morning and it wouldn't take long before "Chubby Cheeks" (the bullied hen) would be standing at the door to her own little "coop". She knew that was HER safe place. I would leave her with another sweet hen most of the day but would go out in the afternoon and let her out to observe her behavior with the other chickens. If they started in on her or she seemed especially scared or stressed, I would let her go back in her separate cage. It got a little better each day. Today, when I let her out of the main house, she didn't immediately run for her safe place, so I fed them all and scattered the food so she could eat freely. Other chickens joined her without bothering her at all and she wasn't "flinching" anymore at every other chicken that came near her. I left her out in the run with everyone all day and although there is still a little bullying going on from one hen in particular, Chubby Cheeks has definitely built up her confidence and now sometimes even stands up for herself against others.She stopped running to hide under me or in the house - although she sometimes will still run to the other end of the run for a few moments before venturing back. I am hopeful that they will all continue to work everything out. Thanks for all the advice and I'm so glad to have something work!