I am so sorry for you and for Kiwi... but I would not act too hastily. I have a few questions -- has she been isoltaed from the flock for a week or more? Is it possible that she continually injures this leg again and again in the skirmishes that result in her being defeathered? If she were mine I would isolate her from the others, keep her calm and quiet. I would amp up her nutrition -- vitamins, protein. And I'd give her a week. If you don't see any improvement after this regimen then I'd say you really did everything possible -- but if she is being injured again and again she may not be able to heal. That's what I would do.
And again, my heart goes out to you,
Jenny
And again, my heart goes out to you,
Jenny