Try putting her back and just observe to see what happens. Every flock is different. Often if it's only been a few days they go back with no problems. There may be some minor pecking order stuff, a peck, a run, but that's it. If there is all out attack or bullying, then you will have to go slower. In that case you either put her in a wire crate, or in a smaller fenced area within the area with the rest of the birds, so they can see each other but not get to each other. Leave it that way til attention dwindles, there is no posturing, etc. then you try to integrate again, with supervision. After only a few days separation, with an established flock, it may be a non event and everything will go fine. Longer separations usually mean longer reintegrations. When a bird requires separation for healing or treatments, but doesn't need total isolation/quarantine, if they can stay in a wire crate with the flock for that time, then it makes reintegration easier.