I respect your attempt to gain knowledge and experience. But moving eggs before they hatch for no reason? .... is that wise? IMO if you have a good breeder and father, don't stress him by removing his eggs. Let nature take its course.
Since you plan to move them anyway, why not spawn the breeders in that tank? Unless you plan to mass produce using a number of pairs but only have one grow out, I don't see the point of this method.
I'm not trying to discourage you. I just don't see the logic to what you are trying to do. Anyway, the key to successful breeding is suitable water. If the fry can survive in your water, they have a chance. So try to keep its perimeter stable at least the first week. By moving eggs/fry means they have to adjust to their new water.
I've often experienced unexplainable losses. Believe me it's frustrating! During this period, I'm reluctant to do pwc. To me, stunt fry is better than dead fry. I truly hope you figure out what went wrong.
Keep us posted. Good luck.