so an update. Two days ago, I found her under a bench in the coop, pretty much refusing to go out into the run. So I let the flock out, locked them out, and then chased her out into the run.
That night I went down and let the flock back in. The next day I was ill on the couch and let them be.
Yesterday, I went down and she was out with the rest. I did set up a third feed station behind a mini wall, and I waited around long enough to make sure she was getting to eat.
She did get some mean old pecks, but she is quick, and one old biddy was pretty positive if the new bird was eating it, it should be hers... but she is slowly fitting in.
A single bird addition to an established flock is a tricky thing, but so far it is going ok. I think it is a help that I have added birds before to this flock.
Mrs K