You "candle the eggs". When my tiels get ahead of me and start laying eggs and sitting on them. I get a flashlight and a dark piece of plastic (a coffee lid works good). Put a hole in the plastic just a little smaller than the egg. You will be able to see through the shell. If you see some red it is viable. If you just see the yellow yoke or it is cloudy it is not.
More likey than not your birds know they are not viable.
Trying to feed a new born will be a b.tch. If your birds don't want them - get rid of them.