I would let them hatch in coop... and switch the whole flock to a flock raiser with oyster shell on the side for layers. It cost me $17-20 depending on which store I go to for 20% protein Purina flock raiser. Which I use because I always have broodies, chicks, roosters, layers, molters and so on. Last year had 82+ birds. Only the layers need that much calcium. It actually is a very practical solution (for me).. and actually more nutritious for most hens... but especially if they are dual purpose breeds and not light bodied layers like leghorn. The usual 16% in layer is the MINIMUM needed to sustain a hen during lay. I don't aim for minimums and higher protein (22%) was actually shown to give better hatch rates.
She likely won't leave the nest once hatching starts until the chicks are ready... has been my experience so far. She spends time clucking to them and they peeping to her so they can learn each others voices and not get separated when the leave the nest. I do however sometimes block them in because if a chick gets out might not be able to figure out how to get back into the nest and mum won't leave until all are ready. So the early adventurer may have a chilly fatality. I provide food and water very nearby broody mom once chicks start hatching and not before then. She has to go out to eat during incubation. My gals seem to pay attention to the weather and try to go out when it is warmest while sitting on eggs... however, I'm on Ca coast and so cold isn't quite the same as it can be other places. Make a nice thick layer of shavings or whatever you use (to help insulate the nest from underneath and mum will do the rest.
If you do let her sit.. it's important to mark the eggs very clearly (not in pencil because it rubs off), and check each night for and collect any eggs that may have been freshly deposited by other ladies. Otherwise you risk staggered hatching and confusion for the mom deciding when to leave the nest. Makes for possibility that the early or the late hatchers could end up neglected while trying to care for one or the other.
Whether you can house 2 broody's together will depend on the broody's. I have several in my standard coop at any given time. It can get a little confusing for the chicks since my girls look exactly the same. But the broody's very quickly peck away a chick that doesn't belong to them. Some however will actually co-parent! And when it comes to taking the chicks out and keeping them warm... not all broody's are created equal. I had one who was so focused on foraging she wouldn't listen to or settle down long enough for the smallest out of 3 chicks... which eventually succumbed to something one day when I wasn't home and the other 2 were fine. On the other hand I had a mom raising 9 chicks that never left a single one behind and settled when needed.
IF I was going to bring them in the house, it would be just for a short time to make sure everyone is thriving. Broody poo is the nastiest!
Though they are pretty easy to grab and get rid of since they are so big.
If you aren't ready for chicks... you could "break" both of your hens, simply by locking them away from their preferred nesting site. Wire bottom cage NOT needed unless that's your preference. I use an open bottom pen for daytime and the wire bottom only for night inside the coop. I won't let ANY girl sit if they are under 1 year old... their bodies and minds are still maturing and they will be much more equipped for brooding (pullets are usually about 1 pound lighter than hens. They lose condition and become shaky during sitting (older girls do to, but they aren't STILL growing). I't like letting a teenage raise kids verses someone in their mid to late 20's.
Very personal and tough decision. Every situation will be different... even with the same broody sometimes. And if they are currently broody... they very likely will be again before too long, if you do choose to break them.
Good luck with your ladies. It's a wonderful adventure and fantastic sight to behold!
ETA: Welcome to BYC!
Hope you enjoy it as much as I do.
