I didn't get a chance to try. She never went broody this spring. Upon further reflection, I'd probably put golf balls or fake eggs under a broody until it was time to add chicks. And yes, they would be added at night. I did that a couple of years ago when I had a broody bantam cochin hen. I (thought) I gave her fertile eggs to hatch, but when Day 25 of incubation arrived and there was no sign of chicks, I went to the local feed store and got her some babies to raise. I kept them in the house until night, then put them under her. She accepted them with no problem. (I checked the eggs she was setting on and none had developed)