Hello and welcome to BYC! Glad you joined.
You should be about to keep a breeding flock for a short time in the barn. I assume it would only be for as long as it takes to rid the hens of any unwanted rooster genetics and then collect the eggs fertilized by your chosen rooster and then they could rejoin the flock. If that is the case I would make sure that the main flock could still spend time with and see the breeders through fencing to minimize issues when the sub-flock is reintegrated.
You should be about to keep a breeding flock for a short time in the barn. I assume it would only be for as long as it takes to rid the hens of any unwanted rooster genetics and then collect the eggs fertilized by your chosen rooster and then they could rejoin the flock. If that is the case I would make sure that the main flock could still spend time with and see the breeders through fencing to minimize issues when the sub-flock is reintegrated.