Thanks all. After reading your posts and doing some more research, my husband and I have come up with a plan. We're going to keep the hen in the side of the nesting box she's in so she'll keep sitting. I don't want to move her and cause her to stop brooding. My other hens have already started to leave her alone and have been laying in the other nesting box. We'll screen her in with hardware cloth closer to the time the eggs are due to hatch. This gives her about 24 x 12 inches to herself, room enough for food and water. That way, if some hatch and I'm not around to immediately put them in the brooder, they should stay contained. Once all the chicks are out, they will go back to my friend to raise in her brooder. My girls free-range and I'm not set up to raise chicks outside.
Now I just have to see if I can figure out how to candle pheasant eggs.....