How big are those nests? One problem I’ve had with a broody hen hatching in a small nest is that the first ones to hatch often like to climb up on Momma’s back. In a small nest they might miss the nest when they fall off. The nest I had that problem with was a cat litter bucket with a top measurement of 7-1/2” x 11-1/2”. Momma was just too close to the sides. Four different times I had to toss a chick back into the nest because they fell to the floor. I don’t have that problem in the nests I built, but those are 16” x 16”. A 12” x 12” might be big enough, I’m not sure. How close to an open edge is she sitting?
I’ve seen a hen get her chicks out of a 10 feet high hay loft. Momma said jump and they did, then bounced up and run to her. That nest above was about three feet off the ground. The chicks were not hurt by that fall, to me the potential fall is not the issue. The size of the nest is.
How many eggs total are they sitting on? Are they all due to hatch at the same time? That could influence your options. Some people have great luck with multiple broody hens hatching in the same nest and raising the chicks in the same area. Some people have great luck with different broody hens on different schedules hatching in nests side by side. Sometimes the hens fight over the eggs or chicks. I once had a hen attack another broody just as her eggs started internal pipping. The chicks start talking to Momma after internal pip so she knows chicks are on the way. The second hen heard them and decided to take over the hatch. They destroyed about half the eggs. With chicken behaviors you don’t get any guarantees, one way or the other.
If one hen can cover them and they are due to hatch together you can try moving one hen. If she accepts the move you can give her all the eggs. If not then that option is not available.
If you decide to move one, I suggest modifying the nest so you can lock the hen in it. Keep it as dark as you can. Use some sacrificial eggs until you see if she will accept the move. If you mark them so you know which is which you can temporarily put her good eggs under another hen, depending on hatch schedule. You’ll have to manage those details.
When I move a hen, rare but sometimes, I move her at night and leave her locked in that new nest all the next day in the dark. A broody is used to sitting on a nest all day, it’s not cruel to her. You can try letting her out just before dark to see if she wants to eat and drink, but I usually don’t. Just open the nest the next morning and see what she does. Be a little patient, she may not immediately go back to that nest, but might later. Or she may not accept the move at all. Make sure she cannot escape that new pen she is in and return to her old nest.
If you leave a hen locked in a nest, make sure it is not an oven on a sunny day.
Good luck!
