Well a broody hen will sit in the nest and not get out. If you put your hand down to take the eggs she will probably raise her hackles and make some ungodly noise. She will softly cluck, and, if she is still doing it after three days it is safe to say she will brood eggs for the full 21 days. After three days of this behavior, at dusk or later take her old eggs out and put the eggs you want her to incubate underneath her. It is best to actually move her to an enclosed quiet darkish place by herself. She will only get off the nest once a day and take a massive stinky broody poop. It is a lot easier to have hens brood the eggs because there isnt much you need to do. Just keep her away from other birds and keep food and fresh water close by. Also give her good food, maybe some scrambled eggs because she probably will lose a lot of weight. She will not lay eggs for about 9 weeks, the 3 weeks of brooding and 6 weeks of raising chicks. I have found there is no sense in taking the chicks away earlier because the hen is still into the 'zone' and then the chicks are your responsibility to raise, again more trouble.
You can raise tamer chicks by incubating your own, if you are successful hatching them, and you spend sometime with them each day. And your hen will continue to lay eggs for you.
edited for mistakes
