Is she sitting on eggs? Did you give those eggs to her all at once? Did you mark them? Is she brooding in a nest box where other hens can add to her clutch? How high off the ground is her nest?
Sorry for all the questions, but they are important ones. If you let her collect a pile or other hens keep contributing, not all the eggs will hatch at the same time, leaving partially developed chicks unhatched, when she gets up to take care of the ones that already hatched. If she's sitting on too many eggs, she won't be able to keep them all warm enough for development. Generally, a hen can cover about 8 to 10 eggs. If you let her brood in the coop, you can try putting her and her eggs in a dog kennel for a bit of privacy. That way the flock will still have contact with her, but they can't add to her clutch. If you choose to separate her, integrating her and the chicks will be a bit more difficult as the flock will see her as a stranger after being gone for so long.