So why on earth is this man here your overlord by succession? Whether king or noble?
Is he divinely descended? Did a god appoint his ancestor? Was his dynasty awarded the mandate of Heaven -- obvious from their victories? Was his ancestor elected by his people to lead them?
This would become kinda crucial if, for whatever reason, the line of succession is not straightforward. In my own story, there's a cousin -- who's in the female line of descent and more crucially descended from a morganatic union. There's also a more distant cousin, exiled and disinherited by the dead lord.
Were there a king, he could rule on the matter. Without him. . . .
I think they're going to go by the election theory and the morganatically descended cousin is going to get the honor. Assisted perhaps by the dead lord's favor. But as usual, the succession went by customary laws, and when life diverted from custom, who was to say what would happen next?
After all, it would not be simpler by any other route.
The Mandate of Heaven is somewhat straightforward -- though the historians have done quite a bit to smooth off the edges, increasing the virtues of the founders and vilifying those who lost the throne, and making the succession of one dynasty
The divine sanction would be a wellspring for religious authorities to try to claim control. Or the manufacture of omens and oracles -- possibly complicated by actual ones, or at least things that can be interpreted so.