The distinction between those two things gets a little tricky for me to hold on to when one of the things that significantly contributes to my expectations about the existence of someone is precisely how much I value them existing... or, more precisely, how much I expect my future self to value them if and when the opportunity to create them presents itself. E.g., if I really don't want a child, my expectation of a child of mine existing in the future should be lower than if I really want one.

Conversely, if I expect an entity X to exist a year from now if things remain as they are now, and I judge that X would, if actual, make the world worse, it seems to follow that I should take steps to prevent X from becoming actual.

It seems moderately clear to me that, while I value more people rather than fewer all else being equal, that's not a particularly important value; there are lots of things that I'll trade it for.