Honestly, I always left any infertile eggs if they were stuck to others. Not worth the risk of damaging the surrounding eggs imo. It also solves the problem of the eggs shifting positions. When I've done this because of the sticking issue and ended up with mold problems (doesn't always happen though), you can use some mouthwash and q-tip to wipe the mold off and it inhibits the growth to a point without damaging the babies around it. Then again, this has always been with corn eggs. You could probably prop up the other eggs with a a stress ball or any other round object. Even plastic wrap wadded into a ball would work if you do manage to get it separated.