If the broody has not abandoned the nest then put the chick back. She will know if the others will hatch and stay on for a few more days to let them. Then she'll bring the chicks out to eat. She'll brood them, sit on them to keep them warm when cold and show them food and water. Protect them from the flock, raise them until she deems they are self sufficient. Or she may not be a good broody and abandon them immediately but that's something you watch for not take the chicks.
You don't let birds stay broody indefinitely. It's horribly draining on their health to incubate birds. It's a nice break for them to brood the chicks as they wont lay eggs during that time either.
