I put a kennel inside the coop and had water and food in it for Mama and babies (6). I kept them in there 24/7 for about 5 days; after that, Mama wanted to take them outside. They were in a closed 10x10 pen all day and in the kennel at night and they were fine. At about 2 weeks, I just let them out with Mama.
The one thing I will say is that I fed them separately; the big girls tend to steal their food and bully them otherwise.