Mine did go broody in one of the nest boxes. The year before I had had a hen go broody there, and moved her away from the other hens, and 3 days later she left the nest and went back to "her original nest'. I lost the clutch. So this year, I left them set where they wanted. And as it was in the hen house, they were safe.
I have 8 nest boxes, but usually they only use 2 nests. So I block off the others. When she and her sister went broody side by side, I just opened up a third nest for the layers, and let everyone alone. My nests are a one bird at a time, and no one laid in their nests.
I set up a card board box on its side, threw in some hay, and the day they hatched, within 24 hours she had them out of the nest, it was about 2 1/2 feet off the floor, and on to the floor and in the box nest. At first both sisters used the box, but once the chicks were more mobile, one of the sisters went back to her nest at night, and several of the chicks would fly up there, and crowd under her at night. The girls shared the mama duties and I kept them right with the flock and it has worked great.
For the first two days, I got down early in the morning, and let the layers out to free range, keeping the hens and chicks in the run. But then I just let everyone out and they did just fine. The mama's would put the chicks to bed a bit earlier than the layers, and neither let the layers pick on the chicks till they were much bigger, and then it was just pecking order stuff.
good luck, Mrs.K