There is no official information on any of their father except that Scar was not Kovu's father. But as Scar was not Kovu's and any of the cub's don't refer to Scar as their father, it iis unlikely Scar fathered any of them. And it is also likely they did all share the same father because the movie did not mention different fathers.
But as said; there is no official information on the matter, apart from Scar not being Kovu's.
Yes. In fact they all do have the same father but he's unknown. Scar isn't the father ether. Zira is his follower and it never shown her and Scar in a relationship, Zira is most likely the same age as Simba but slightly older. Nuka, Vitani and Kovu's father is a rouge lion who is unknown.
i'v seen the lion king 2 and its very possible that kovu and nuka have the same father then again nuka could be scares but do know vitani is not the daughter of zira she looks like she could be nala daughter and she could get the shape of her nose from scar zira has a black nose there is no other lions that have blue eyes her màu hồng, hồng nose probably came from nala hoặc simba but Disney never gave there back story so it hard to say