MY suggestion is to make it possible to sell an unhatched egg. By using the Breeding Calculator for your breeding combos, you will sometimes know what the egg is that is incubating before it hatches.Once it is on the nest you know right then if you need it or want it. Why make you waste valuable time twice for an unwanted egg. I could sell the unwanted eggs right off the nest and get busy breeding again. Then I've only lost 10 hrs instead of 20; 16/32 etc.