Hudsonia is usually Gavelkind and actually 3 kingdoms, it should split up on a decent succession. Wait and plot for your time to strike.
Are you sure about that? Hudsonia is, as far as I know, only one kingdom that usually is pretty stable until it gets knocked around by some form of outside invasion. It has fairly loyal vassals that will convert, so long as Deitscherei maintains control of it's Holy sites to the south for at least one, maybe two, decades.
I'm loving this game as occultist but I'm having trouble making that hurdle to reform them. My main problems are at least negative 12-20 moral authority at any given time due to other occultist loosing holy wars. That and going up against the kingdom of Hudsonia is a daunting prospect and they control 3 of the holy sites. Anyone got any tips?
I find that once you control New England (all of New England), and have about a dozen or so single county vassals, war with Hudsonia becomes much more manageable. You go into Albany with a nice strong spearhead assault, while your vassals swarm around you. Hudsonia will require either two Holy wars, or two claims. With Holy Wars, I usually wait until someone has taken care of Deitscherei (someone always seems to). Manhattan, however, is usually captured or ransacked at this point, or is otherwise so weak, it cannot support the troops to resist an entire New-England Army.
For the first plan to work, you do need to have tribal authority at 3rd level or lower. You need your vassals
entire army, otherwise Hudsonia will (usually) be able to take care of you.