Death of King

[Vasiliy]

Hi

If I assigned one of the king's son (not a heir) as cleric will this cleric disappear after king died and other son (heir) became king or this cleric will live forever?

Thanks

[Lord_Nick]

The cleric will live forever (unless he becomes Patriarch).

Your unmarried princesses and non-heir princes that are not part of the Royal Court will disappear though. I assume the married princesses will still be part of foreign courts, although they will not appear in your Royal Family. I have not tested this to be 100% sure.

[Gallifrey]

Right. Any royals that are part of the court (marshalls, clerics, spies etc) will remain there after the death of the king and live forever barring any violent ends. Clerics may get "hired" away as Patriarchs or Popes however, and there they will eventually die.
Any male royal that is not assigned to the court will vanish with the king, along with all princesses. The ones that were married presumably go to live with their husband in whichever country he belongs, and the unmarried ones, well, I guess they mope around the royal estates forever unwed and slowly going mad... Or get interred with the king if that's how you like to imagine things ;)