Gaps in family trees? (fanfiction)

So, as I said in another post I am writing on a series of fanfictions spanning multiple generations. The problem is I cannot connect all OCs properly, so there inevitably are some OCs that cannot plausibly be kittens from the previous generation. Would it bother most readers if there were some gaps in the family tree? I have a plausible in-universe reason if asked, but still.