So does that mean that
CharacterTeleportPartyToTriggerMovieLoadState(TRIGGER_CYS_Start_P1,"MovieGameIntro_Finished","MovieGameIntro");
teleports only the characters that were in the Char Creation ?

If one already knows how many pairs get added to creation in which order, it should be possible to teleport them to Cyseal 'silently', with CharacterTeleportToTriggerSomething() and do the Movie teleport for the final pair, would that work ?
Is there some kind of 'Back' button in char creation to go back to the previous pair ? If not, can't they be teleported directly and silently ?

(Just asking out of curiosity, I have no plans to create any 'more-than-two-players' mod.)