Your hens are just gorgeous! They are very, very fortunate to have ended up at your place, with a mother who loves them like you do. You have provided a beautiful coop for them and it is obvious you take very good care of them. I have no doubt in my mind that you will continue to meet their needs and they are going to do just fine over the winter.
In 2000 I was in Ayacucho, Peru, way up in the Andes Mountains. To go to the airport, we hired a taxi (aka, someone with a car who gives rides to tourists) for a few dollars. He transported us out of town and helped us unload our luggage from the trunk of his car.
Then he said to me, "Senora! Por favor! Mira!" He pulled back the lining of his trunk, and there between the lining and the metal body of the car were 5 or 6 baby chickens about 2 or 3 weeks old. Someone had given them to him in exchange for a ride, and they were just hanging out back there. When he stopped, he would offer them some water from a cup. Whatever they did not sip during a stop, he threw out.
Chickens are a lot more hardy than we give them credit for. Around the world they live in conditions we cannot even imagine. They are tough. Very tough!
Your birds are going to have a great winter!