Candle them every few days. ( you will see the baby embryos doing backflips!) If there is a possible dead one, candle it and one other almost every day( a good egg and the bad egg) Say, one stops moving, you grab a good egg, wait a few days and candle every few days, if the development is not very close to the good egg, wait maybe if your not sure, then toss it. SORRY IF THAT DID NOT MAKE ANY SENSE!!! You will probably need to help them hatch ( THE EGGS ARE HARD!!!) Just take some tweezers ( only if they have a piping hole) and GENTLY peel back some eggshell and membrane. Good luck on your future hatch!