First, let me say that I give advice based on what is most likely going to happen, but of course there can be exceptions. For breeding, it is always best to only have one pair of birds per cage. Some breeders for profit will breed a flock in an aviary because they are more concerned with volume than the quality of the chicks or the health of the birds overall. When housed in an aviary, you should refrain from giving them nests or doing anything to encourage breeding. One of the reasons is your question about who fertilized the eggs. With several birds involved, you have no control over who mates with who. So if something is genetically wrong with the chicks, or eggs are infertile, or other issues, you have no way of knowing which bird should not be breeding. In the wild, many species live in flocks, but when it comes to breeding, each pair has their own nest and territory, and other birds are viewed as rivals and will be driven off. In captivity, if the “rival” bird cannot escape, it can be bullied or killed by the breeding pair. If more than one pair has a nest and eggs, they will often destroy each other’s nests, eggs or chicks as territorial behavior.
You have accidentally created a very confusing situation for your birds. Your hand fed male is torn between being a devoted breeding bird or being a pet. Hand fed male cockatiels can be a problem when it comes to breeding. Some of them get too possessive of the nest box to the point of attacking the female and not allowing her to access it. I am afraid your tame male may be headed in this direction. There can also be issues if the eggs hatch. If fighting starts between the adults, the chicks may be the ones who pay with their lives. The safest option is to remove all males except the one the female chose. These two are the most likely to see this clutch through hatching and feeding. I think if you keep all of these birds together at this point, it will result in tragedy. I would keep your tame male in the house as a pet. If left with wild cockatiels for too long, he will end up choosing them and you will lose him as a pet. Regardless of what you decide to do with him, I would still remove all but the bonded male & female from the aviary and leave them alone to raise the chicks. In the future, if you still want them to share the aviary, then do not provide a nest box or anything they can use for a nest.
Thank you for asking Lafeber,