Most likely the others will continue to lay in the one nesting box. There are several possible problems with this. Obviously, they will continue to add eggs to the bunch over the 21 day incubation period. You should mark your original eggs and remove newly laid eggs daily. So the original eggs can all hatch at very nearly the same time, and the hen can leave the nest to care for them.
Sometimes the other hens will drive the broody hen off the nest so they can lay their eggs. Then the broody MAY find another spot, leaving the eggs on the nest to get cold. Or the other hens can pile in right on top of her, and occasionally eggs can get broken that way.
I like to have a special spot for my broody hens. I have built them little broody houses, which are very similar to large doghouses. Some people use dog crates. Others build large nestbox type areas in the coop which have doors on them, so they can close off the other hens, yet let the broody out to poop and stretch her legs every day. Food and water should go inside any of these options.
I always move my broodies off their chosen nest and into their broody box before giving them eggs. I let them stay in the new spot for a couple of days and get used to it, then give the eggs. I've read that others move them at night. Then lock them into the new area so they can't abandon the eggs and return to their favored nest.
Everybody does it differently, so you'll need to decide what is best for your situation.
Good luck!