I currently have one broody on 7 eggs.... yesterday another started. I pulled her out of the coop and put her into the breeding pen with the polish. She's going to have to stay there for at least a week. If she sets up shop there, I'll let her stay broody and put some fertile eggs under her.
My Mom once told me that if there was thunder (big storm) , any eggs I had in my incubators or under hens, would die. Old wives tale. The only storm that would move my broodys would be one that produced a flood & washed the nests right out from under them!