I would candle them and mark the ones with the largest blob inside. Maybe number them and keep track. Candle them again in a week and check to see if same ones are still larger than the others. Remember that some of the originals might stop or might not have been fertilized. How many days do you think there is between the new ones and ones you put in?So I believe I have a situation. I have 12 eggs due on the 12 however my kids were so kind to put additional eggs in the bator and I don't know when. Sigh what would be the best way to determine due dates