I love the way they all stand up like little soldiers at attention.

And man oh man - can they ever run!
It is too bad about the male being sick, but at least he is no longer in pain.

Are there any other unrelated males who can take his place?
According to the show, only the dominant female of each clan is allowed to breed and have babies. She only breeds with the dominant male. And she does not breed with a closely related male.
In one of the clans that borders the Whiskers, the dominant male has died. One of the sons has beome sort of the dominant, as in he bosses around the other males and protects the family and their territory - but he cannot mate with his mother. One of the Whiskers males is trying to move in and mate with the female and become a true alpha.