I usually don't let a hen sit on eggs in the winter because of the temperature requirements of the newborns more than the issue of just incubating the eggs. If it were me and I was intent on letting her continue with this I would bring her inside and then be prepared to take care of the peeps indoors until they are feathered and big enough to go out. If you have electricity in the coop and can do all that out there with a heat lamp, then it would be much easier. But you were certainly right to separate them.

hi,
the chicks hatched Christmas day. Mother hen and chicks are doing well...inside.

What a great Christmas Present. Congrats and enjoy!!

Stacy

Now they'll need to be kept indoors for about 8 weeks or so, unitl they're fully feathered and large enough to withstand the cold. The last thing that you want to do is to put them outside in subfreezing temperatures when all they've ever been accustomed to is a nice warm house, or even a cool basement.