Papyrus Help: Reverse Searching Relationships

[The Man in Black]

Does anyone know if it’s possible to generate a list of all people that an NPC has a given type of relationship with? If you already have two NPCs, Actor1 and Actor2, it’s easy to check whether they have a relationship with Actor1.HasAssiciationType(Relationship, Actor2). But is there a way to do a reverse look up? To find Actor2 without having to essentially run a boolean check on every single actor in the game?

 

Or, more concretely, is there an easier way to find out who an actor’s siblings are without checking whether every single actor in the game  has a sibling-type relationship with them?