Funny enough, for a concept I have worked out, this isn't an issue.
It's part of a setup for an elven queendom, where a queen-to-be is required (by law/founding charter) to find at least three consorts who she wants to also have as her councilors. Those consorts would then be required to take a specific ritual oath of loyalty that includes some other magic. Part of that magic ensures that every consort will be part-father of every child of the queen.
This also means that each time the queen wants to conceive a child (which is always a daughter), the queen has to sleep with every councilor at least once, or the magic will not fully implement.
Another aspect of the magic is that the queen will always 'breed true': her daughters will always be effectively full elves, no matter the species of her fathers. But some aspects of the paternal lines are always incorporated, so the royal line has some potent magic affinities from other bloodlines, such as kitsune levels of talent with illusions.