It`s not very likely that rogues fathered all these cubs... From a realistic point of view: All the cubs in a lion pride have the same father. So from that point of view, all these cubs are Simbas half-siblings.
But I doubt that is the case in the TLK universe.

lol
I honestly don`t think the writers/artists of these books and comics where these cubs appear, have given any thought to who their parents are, it`s just not important to the story. New cubs are fun and interesting and add new dynamics to stories about Simbas cubhood. Who fathered them is kinda uninteresting from a reader`s point of view.. in my opinion.
But I see your point. Lions like Joe and Ni are visiting the Pride Lands for the first time, and so they could not possibly be the father of any of these cubs.. Mega (who appears in TLK6NA) could perhaps be the father of some of them?
I don`t think Scar has any offspring (except Nala, in my theory) and Mufasa is the pride leader. Yes, he has Simba, the heir, but that doesn`t mean he never had any other cubs with other lionesses than Sarabi. Like I mentioned earlier, all the cubs in a lion pride have the same father... But I don`t think TLK is THAT realistic.
