Hi,
If this was her first clutch, it’s very common for it to fail because the pair is still learning what to do. But if she has done this before, then it’s best not to try to breed this pair again. Not all birds are good breeders or parents. Losing the first or second clutch is normal, but if it keeps happening, a pair should not be allowed to breed anymore. The problem with fostering the eggs to budgies is the size difference. You will probably either have to supplement the chicks, or pull them to hand feed. At some point, they will be too big and the budgies will likely stop caring for them.
Thank you for asking Lafeber,
Brenda
