One should never spare the boot on a deserving rooster!! (said by this old wise man living in the banana belt)
Layers, I would move the broody hen into a Box/cage that is very windproof, if possible with a ceiling/roof on it. Put a door on it so you can lock her in it. Maybe even another heat source, pad light or something for when the babies hatch.
I rear my babies outside, in a "coffin" to start with at a couple weeks I open a door to a larger cold are. I move the feed and water out there as they grow. With the it close to the door to the heated area.
They learn fast to come out eat and run for the heat. I later open up a third cold compartment for the. I have two of these. The one allows me to heat the two end units so I can raise two batches at once. You should construct something similar so the chicks do not die on you. Good Luck