If this is somehow in the wrong section, please move it.
So I set many families due with new children manually all on the same day an hour or two apart from each other (starting at 6am Saturday since that's when most employed Sims are off work), ensuring one specific family couple is last so their children have traits I personally select for...reasons...afterwards (though this doesn't apply to Sims who will later adopt due to no partner).
But what's happening is that when the children of inactive families are born, they are immediately 1~2 days away from aging up, while my active family's children are 20~21 days (21 is what the baby life stage is set to) which is incredibly annoying as I have to use the "Trigger Age Transition cheat on the active family's newborns (3 of them; they are triplets resulted from genie wish) so they keep up with aging.
Am I right in thinking it has something to do with Daycare? If not, does someone know why this happens or am I going to have to go through with it every time new children are born?