GetCombatGroupMemberCount

Returns the number of actors that are in the run-on actor's combat group — that is, the number of allies that are fighting with the actor. Returns 0 if the actor is not in combat, or if they are in combat but have no combat targets.

Once an actor is killed, they are removed from all combat groups. This means that while this function is usable for determining whether an actor is fighting without allies at their side, it is not useful for detecting whether an actor previously had allies who have since been killed.

This appears to be the non-deprecated version of GetGroupMemberCount.