you want all the eggs to be the same age, with my first broody experiances i gave my hen one egg a day (becuse that was all i was getting at the time) and only two hatched out of the 8, and they die a few weeks after. you want to give them eggs all at one time, mark them with pencil, and every day take out the unmarked ones. that way all your chicks will hatch at once and your hen wont be stuck on the nest forever. Anyway, if your letting her keep the chicks, she will just follow the fist chicks to hatch and leave the rest of the eggs to die.