Thank you for checking in! My husband and I agreed that a low temperature oil filled radiant heat radiator would be a good idea, and set it so it was just above freezing to help them. I gave them canned fish to help with feather growth and to help them with generating warmth along with a little grain before bed. I also put water inside, and the water inside was drank too, but also left food and water outside. I have a doubled canvas cover stapled up for the door so the windy air wouldn't come in as easily when I opened the door. The girls wandered in and out all day to warm up, eat a few nibbles, scratch, and come back in. They stayed with their feathers puffed up most of the time. So they did okay, I think one girl may have a little frostbite on one tiny protrusion/spike on her comb. I checked the inside of the coop to check of fogging up, or frosting the windows, or anywhere in the coop and it never showed up. I checked on them a few times a day. .