I'd leave her be or next thing you know, you'll be taking in all the feral chickens and be overwhelmed.
My neighbor's chickens free range. It's sad seeing the chicks slowly dwindle in number and the adults disappear too sometimes, but they keep getting more chickens when they get down to one or two. Same happens in the wild population. There will always be some that survive to reproduce and add to the population. Their chickens stay on my property most of the day, that's why I see the chicks and adults go missing. I did find a stray chick once during a storm and put it in with my silkie that had chicks because I thought one got out. Took a few days before I realized my mistake, but my silkie raised her and now I have a random game bird pullet.
I'm rambling, but my point is, let mother nature take its course.