Why not just say that two situations where there is one more person that came into existence in one situation than the other, but everyone else’s “time in which

Why not just say that two situations where there is one more person that came into existence in one situation than the other, but everyone else’s “time in which they are alive” and “how happy/satisfied/whatever they are” are the same, are morally incomparable? So, that way, there is neither an obligation to try to make it so there will be more people if they would be happy, nor an obligation to not do so if they wouldn’t be, but there is an obligation to, if you do make a person, to endeavor to make situations good for them? So then, future people’s well-being matters, conditional on them existing, but without an obligation to try to influence whether they exist or in what numbers (beyond how this influences people who already do exist or who will exist regardless ).