When were your chicks hatched? Usually the hen will leave the nest on her own 24-48 hours after the first chick is hatched in order to take care of the needs of her new babies. If you have a staggered hatch (eggs added to the original clutch after the initial eggs are set) then there is a good chance that the hen will leave the nest before all the eggs are hatched--if or if not the eggs are viable. If that happens, you have the option of candling the eggs and putting them in an incubator to finish hatching and then returning them to the hen and her little ones. If you do that, best to try the reintroduction at night and observed them for signs of rejection.