I got this idea from reading @S5apiotrowski's thread and I didn't want to hijack.
I set eggs in my igloobator for a Thanksgiving day hatch. The Sunday after I set the eggs I had a Silkie/Ameraucana cross go broody so I gave her 6 Cayuga duck eggs and put the 3 chicken eggs she was sitting on into the bator. Well after 14 days I candled the duck eggs and they were all clear. (I need to give my drake a pep talk). So I gave her back the 3 eggs she originally had because I really didn't want a staggered hatch.
I had 15 hatch in the bator this past Wed & Thurs and yesterday 2 of the broody's hatched. Today I built a large brooder in the garage in case it ends up being too cold to get the chicks outside before spring. Here is where the idea comes in. I moved the broody and her babies from the nest box in the coop into the garage brooder and slowly introduced the bator chicks to her. She accepted all 15 of them! The only hiccup is that she didn't want to continue sitting on her last egg. I candled it and it had internally pipped so It is in the bator. Once it hatches I'll sneak it under her.
Here are a few pics of mama and her foster kids in the garage brooder.