i don't think it would hurt her to sit fake eggs- i had a broody that the first eggs didn't hatch, so i gave her another set- so she actually sat 5-6 weeks rather than 3
Sorry Tripp thought it was answered. I would leave her on fake eggs for a week and a half then put her on real eggs for the 21 days. Is that enough time? Topsy sat for 14 days on duds and then 21 days on shipped eggs. Miss Lydia had a broody sit even longer.