one group of birds using 2 coops?

If you build it, they will come. Just attach it to your run. Your flock will separate and use them both. They are like us--they will fill the space.

 

I have FIVE coops (of different sizes and construction styles). Had to build/buy/create more because of the increasing size of my flock, too. Gosh, I don't know how that happens, do you???

Anyway, there's a main coop, an A-Frame coop currently used just for laying... nobody sleeps in IT. It was monopolized when Buffy was broody on her eggs, and when she raised the only chick that hatched. Then there's the Duck House, never used by the ducks but I appropriated it as a grow out coop. Those four chicks decided that's where they want to stay at night, permanently. There's a specially-built, purchased coop with attached run, used as grow-out for another batch o' four chicks, and they are in residence in it even though they're not chicks any more. Then there's the Little Tike's Playhouse coop, where four others sleep.

So, in my case, everybody goes back to their original coops at night. They DO visit the main coop during the day, and Buffy has returned to the main coop WITH the GrandChick, who roosts in there now. Some of the residents of the main coop visit the Playhouse to lay eggs in it, some lay in the A-Frame, for a while somebody would lay an egg in the Duck House, but nobody has started to lay in the grow-out coop with attached pen.

I consider it all The Olmstead Homestead - it's rather like a commune compound. Friendly visitors from one or another coop to all the coops, roosts, and nest boxes. I'll be adding more coops as necessary, too.