Maybe we're misunderstanding each other. The hierarchy is religious family -> religion -> faith. There's no such thing as two different religions from the same faith, but there can be two different faiths from the same religion, like Catholicism and Orthodoxy are both faiths of the religion Christianity.

Most religions from the same faith aren't friendly with each other*

@Half-lidded Bruiser You could, but most christian faiths aren't friendly with each other so it wouldn't make much sense and if your religion was righteous to another, you would get +20 to opinion modifier already so it would be overkill.

Uhhhh, BASED?!
I do have a recommendation in the scheme advancing effect: change the "same religion" check. I see a few, better options. You could change it to "same faith". You could change it to a faith hostility check, ie, bonus if astray or righteous, or just righteous. You could change it to directly check the Witchcraft doctrine for the scheme target's faith, ie, if their faith accepts witchcraft or holds it as virtuous, then you get the bonus. "Same faith" would be the easiest to implement, of course.