@freemo @zleap Ohhh this is getting much more serious than I expected and I love every bit of it!
And indeed, graphs are much more well-suited to describe polycules (and a meeting of polycules, a forest). We could even discuss certain practical implications like variations of min cut problems: "given a fall out between this set of people and their relationships of depth N, what's the minimum number of edges to cut to get two polycules that do not internally hate each other?" :'-D
That being said, the initial idea to use molecule-inspired terminology stems purely from the name polycule itself, being a portmanteau of polyamory and molecule. It's probably not helpful to stick to terms of related concepts for this though!