I always keep the broody mama and her chicks separate for a while because we have a lot of predators and if they happen to get away from mama and cant find their way back they are not going to survive. I really dont know your set-up so I dont know how to tell you to prepare for the newbies. Fresh water and food is number one....Let us know your set-up and we can offer some helpful advice.
We have several "coops" --
1) we have a large dog kennel 12' x 20' converted into a coop/run. There is a small chicken door allowing entrance to a large communal run in the woods. This communal run has welded wire fencing - chicks could easily get through, but the older birds (10 weeks) cannot. Currently our dominant rooster, seven layers, and 6-7 soon-to-be layers roost up there at night. The Broody used to roost in here. There are a couple nesting boxes, but they are not currently being used. We have a small part of this cage partitioned off with a small little coop with 2 Russian Orloff roosters. They stay contained because they will fly high and have been really aggressive and trying to mate with the young birds.
2) we have a 12' x 12' coop/run that also opens up into the same communal run. This has 4 nesting boxes and is where Ms Broody is currently residing. She is joined by 1 layer and 7 birds that are about 12 weeks old. There are 4 nesting boxes in this coop, and recently it has turned into the favorite nesting spot.
3) we have a small A-frame (6' x 8') that opens up into the communal run, but the communal run is partitioned behind the dog-kennel coop (1). We currently have a Barnvelder Rooster in there. He was previously with his brother - who is currently sick and currently in the "recovery" area. I know one option would be to move this rooster into coop (2) and then move the hen & her chicks to coop (3). Coop (3) is the most difficult to clean/maintain/resupply - so this is not my favorite option as we will have others checking up on the birds for us.
4) In a separate part of the yard we have a 6' x 25+' coop/covered run for little guineas. We currently have 14 young guineas in the coop (and 7 more soon to join them). This is fully enclosed. We a Barnvelder rooster recovering from a respiratory illness in with the guineas as well as a Jersey Giant hen recovering from a dog attack. I will likely return Ms Giant to kennel (1) when her egg holding period is up (even though I don't expect her to lay anytime soon) - The Rooster is "okay" - not nearly as red as his brother, but has been eating & drinking and getting stronger - he will live. I can keep him with the guineas, move him back with his brother, or potentially put him in coop (2) when we leave.
5) The "communal run" has a small coop on the ground that serves as a nesting box. We have a coop building project ongoing that will connect to the communal run and the dog kennel coop (1). This will not be complete in the next month :-( We've been side tracked with other projects.
6) I picked up a small unfinished coop (roughly 4' x 4') and elevated 2' off the ground. This is currently to the left of the communal run. We are working at putting up more welded wire fence, which would expand the communal run and this new coop would open into the new part of the communal run. We will maintain the ability to partition off this communal run to separate chickens. This new, unfinished coop does not have much area for a run. It is probably sufficient for baby chicks, but there is little space. I have the holiday weekend with my husband to work on things - I don't know how far we will get. We also have welded wire fencing to put around the entire yard. The communal runs open up into our yard/land, and we let our chickens free-range as much as possible. We do not give them full yard access when we are not around though - too many dogs! Once we get the fence, we will feel more secure with keeping dogs out (and hopefully deterring guineas from wondering off when we let them loose!)
-- As things currently are, I think the best places for momma and chicks are in the coop she is in (but is shared with others), or in coop (1) where the Russian Orloff roosters are. These are the MOST secure areas. Moving the Orloffs is hard. I could put ONE of them in coop (2) - but together they gang-rape the young hens.
I would love to sell some Roosters! I just don't know what "illness" has circulated through my flock and I don't want to sell/give away any birds right now. I recently lost a couple hens to illness and am awaiting necrospy results... Offloading roosters would make things easier for sure!