Most unrealistic portrayal of wolves that I've ever seen!
There's no such thing as "alpha school". The alpha pair are the biological parents of all the other doggies in the pack. You become alpha when you leave your parents' pack, find someone of the opposite sex, hump them, and have puppies; hence becoming the alpha of that pack. To become the alpha of an existing pack, you have to kill the incumbent alphas. The only way Kate would've become alpha of that pack would be if she killed her parents, or if one of her brothers killed their parents and then had sex with her.
And because the alpha wolves are the other wolves' parents, this means that Kate most likely banged her brother. Only the alphas are allowed to have sex, and the rest of the wolves have no-one else to have sex with anyway besides their siblings. Which means that in the unlikely event that Humphrey's not her brother, he would be her nephew from one of her sisters sleeping with one of their brothers-which really isn't that much better. In that case, he probably wouldn't be alive because his grandparents would've killed him, and then they would've kicked the sh*t out of both their daughter and whatever son is accused of knocking her up, as is standard procedure when a non-alpha gets pregnant. This is:
1. To conserve resources.
2. If you caught your daughter having sex with your son, what would you do?
In any case...dude. Your brother. Or nephew
Also, their parents (and that other dude's parents, the one who was with Kate's sister) wouldn't have gotten mad because an alpha was with an omega. They would've gotten mad because non-alphas (which Kate is, since by definition a pack can only have one alpha male and one alpha female) are having sex in the first place. Incestuous sex at that in Kate and Humphrey's case. They would've gotten mad at the younger daughter and the other pack's alpha's son because they're not supposed to be having sex either-not because their son is an "alpha". He isn't; his parents are. The girl's pack can't support all these puppies that would result. He and the girl would simply leave and form their own pack, thus both becoming alphas of that pack.
This movie promotes incest and ignores the fact that you can only become alpha of your natal pack via patricide.