Does a Kyriotate or Shedite have to abandon a host to possess a new one?
The old host is relinquished when the new one is successfully taken over, for Kyriotates who don’t have enough Forces to keep both hosts. Shedim normally have to assume celestial form, leaving one host before taking another, but can also “ooze” between hosts (see the Infernal Player’s Guide, p. 57).