Are you nest boxes on the floor of the coop and how far away from the other nest are they, you could always make a small enclosure with plastic hardware cloth that's big enough to put a small food and waterer in that way she's still part of the flock and it makes chick intro much much easier...
I have my broody momma silkie seperated from the other as of last night I usually seperate them after they've sat on their nest for at least 7 days and then they get moved to the broody momma apartment inside the coop which is a large wire dog kennel so they can see everyone and everyone can see...