Oh my. I have since seen another post from OP that the remaining egg might be a double yolker? Double yolkers rarely make it. If it is a double, I'd not add anymore eggs. If it's a single yolk egg, I'd add more eggs so you don't have a lonely baby.I saw on another thread that you’re on day 3, and these are duck eggs? Next time wait until day 10 or so to make any decisions on tossing eggs. I’m sure it’s happened to most Hatchers at least once.