Shedim and Kyriotate Resonances in GURPS?

[JCurwen3]

How would you build the resonances of standard Shedim and Kyriotates in GURPS 4th ed terms?

Possession the GURPS advantage doesn't seem at all right for the standard Shedim resonance, which doesn't seem to give them control over the bodies they're inhabiting, only "[desensitizing the] hosts to obscenity by bending their minds to [the Shedite's] celestial will, convincing them that such perversion was their idea". That sounds more like the Mind Control advantage, but then there is the sticking point that the Shedite is physically inhabiting the host form too (some extremely limited form of Possession with a limitation?).

And Kyriotates are complicated because they can possess multiple hosts. That could be a combination of Compartmentalized Mind levels and Possession. But that alone doesn't handle the fact that they can only possess up to their Forces in total host Forces. Forces as a concept don't exist in GURPS, but the way it should work is that they could possess a great many "weak" hosts (like all the insects in a swarm), or a human and two dogs, or just several more than two dogs at once, or two humans (if one of them was a child, or two adults if the Kyriotate we were modelling had enough Forces in In Nomine for that). Since character points are a rough indication of relative power in GURPS, it feels like the best way to model it would be to limit their Possession against some total possessible character point value, but I have no idea how to do this.

And finally, Shedim of Saminga, and Kyriotates of Laurence - they can possess the dead. What's needed to model that?