What to do if the hen is having chicks and is not laying on all the eggs?

Just let her be. The newly hatched chicks will take up some of momma's time and the room under her but the mother hen will adjust things by herself. Trying to do this for her will just stress her out and may cause her to leave the nest. The new chicks will find room under her wings eventually and mother hen will roll the unhatched eggs closer together.