If they are eating the feathers, a protein deficiency might be causing that behavior. It would not hurt to up their protein--cut out all corn scratch and high carbohydrate treats, give them high protein treats like small amounts cat food, low-salt fish, sunflower seeds, scrambled egg, meal worms, etc...Do they have plenty of room and stuff to do to keep busy when the weather is not good ?(often happens when they are cooped up for a day or two). Get some Blue kote at your feed store, and spray the pecked areas, that should help a lot. You might want to separate her out if she is in bad shape, especially if there is any blood. If you are using any lights for laying, turn them off.