My initial thoughts are ancient bloodline spellcaster (with Sulani Mana, obviously) (I've got a boatload of such sims) (basically all my sims have both those traits) gives up magic, gets bitten. As a werewolf, my sim has a child with Greg.
Hopefully a child with: Sulani Mana, Strong Bloodline... and Greater Wolf Blood?
Next step, we turn Father Winter into a werewolf. The aforementioned child gives up werewolfing -- hopefully keeping the Greater Wolf Blood trait? there are a few unknowns here -- and takes up spellcasting. This sim, now an accomplished adult, adept at painting which is the sign of adulthood, has a child with werewolf Father Winter.
My hunch is that Great Wolf Blood, if that's the right name,
won't pass on if the parent that has the trait isn't a werewolf. But I'm curious to see how that all interacts. Does a child have a chance to be born a werewolf with an ancient spellcaster bloodline? Or does the werewolf part mean you get nothing from the spellcaster parent?