They are Muscovy (6) girls. That's interesting the number of eggs they would need to go broody.Breed again, sorry I forget. Crack one open and look for the bulls eye. My Muscovy's will go broody on as few as 2 eggs them girl's don't need any encouragement .So if they are fertile leave them.
https://www.backyardchickens.com/t/16008/how-to-tell-a-fertile-vs-infertile-egg-pictures/50