Chickens are awful creatures honestly, and willing cannibals.
If there is ANY skin showing - or worse, a speck of blood - they will pick at it. I’ve witnessed them open up another hens abdomen and eat her alive from the inside out.
So if she goes back with the others she needs to be FULLY healed first.
Also chickens sense any other chicken that is… a few cents short of a dollar if you know what I mean. One that’s not as quick to react. Or one without the vicious instinct. If she’s a really tame, sweet type… just don’t put her back with them. They WILL kill her.