That's the problem with having other hens lay eggs in her nest. She might add the new egg and kick out one that was partly hatched. Sometimes they get too many eggs to keep them all warm, and you get a really poor hatch if any. Put on a glove if the picking is too harsh. Or put some chicken wire up to keep the others out, you can take it down in the evenings so she can get off the nest and eat and drink.
