Hurry up and wait is a human emotion, hens only understand hurry up and do something. You will likely loose the chicks in the last eggs if they're 3 but especially if they're 4 days behind the other chicks. Hens in and by nature are predisposed to only sit on eggs that she laid herself so all chicks will hatch more or less together and the hen can then begin showing them how to make their way in the world. Hens have non of the milk of human kindness that you or I possess nor do hens comprehend why you would expect her to remain on a nest when all her instinct from the days of the Dinosaurs to the present tells her that she needs to be out and about raising her already hatched brood.
If you force her to stay on the nest she will likely become restless and trample the whole litter to death. Only in a totally dark, quite, and cool location will a new hen mama remain still past the 23 or 24th day. And that is still short of the 4 days behind the hatching date of the first chicks. This is the reason that the Egyptians first began artificially incubating chicken eggs. The reason was so they would not be tied to the hens' timetable or predisposition but instead decide when or where they wanted their chicks to hatch, especially if they had more fertile eggs than setting hens available to brood eggs. Trust me, chickens do not see the world through the same lens that you or I do. If the last few eggs mean much to you setup some kind of hatcher to finish the job in case the hen refuses to do it.
Don't sweat a baby chicks taking a header out of a nest box. I have seen probably millions of them taking a 3 story leap from the conveyor belt in the incubation room to the sexing, vaccination, and packing floor in a commercial hatchery. If anything it seems to help more than hurt them. I do know that a baby wood duck in the wild seems to survive better if its first life experience is a 40 foot or greater fall from a natural tree cavity to the forest floor, sometimes hitting a dozen or more tree limbs, and tumbling bill over butt all the way down. I know that it is hard for some of you to watch but think of it as natural organic chick birth.