I have seen my hens do many different things . roll some bad eggs out of there nest. sit on bad eggs until the chicks hatched then she abandoned them . And one time I saw her eat an egg with a dead chick inside sharing it with her chicks.I had food and water for the hen and her chicks. I have a hen sitting I wrote down the date when I saw her lay and I am going to wait twenty one days and see what happens. I will give a few extra days for the late eggs to hatch. then I will take the eggs. The kids will dissect them and study there cause of death.I believe we are always learning when it comes to chickens not all chickens are alike they have human emotional behavior. They amuse me by there reaction to there surroundings and with there emotional attachments to each other.The rooster towards his favorite hen, There sleeping habits and how they sleep in the same place and order in which they sleep with each hatch it is different not knowing what the hen might do .With hens sitting on there nest it takes time and patients and learning when and not to mess with the hen and her hatching process.