All good ideas that I have used successfully to integrate birds.
I have multiple pens and if I need to move one to another breeding group, sometimes I just move 2 or 3 birds around from other pens into that pen as well to confuse the resident hens. I can normally move the others back without issue a couple days later.
Or just get some birds like my dominiques. I can plop a random hen in the pen in the middle of the day and they look at her and move on, lol. Love those birds! Let us know what you do, I'm curious how it works for you!
My WRs are the same way....they just have more things to do with their time than pick on other birds unless it's long about meal time and that new bird gets into their feed space, then they'll slant them a peck to get them to move over.
If everything else fails, I've done some one on one flock training that has aided an outsider/loner to be able to eat at the feeder and be more accepted within the flock that may work.
It sounds like she's going to a good home, so that's a positive outcome for her. It's a pity your flock won't accept her though, having tame hens around are nice.