NPC Organization Best Practice? Multiple Lists?

[Mettius]

I watched Ken Shaw's video on organizing Realmworks and liked the way he was using cast lists to contain NPCs for a particular region.

So an organizational question for those of you who've already tried out a few methods.

Case: A given list of NPCs part of an organization (Military Outfit) and some of those NPCs are also part of a ship's crew which may change over time.

How best to represent this?

I started out with a Nested cast list for the crew underneath the Military Organization cast list.

<Band of Brothers>
|
--<Ship of Fools>
|
--Bob
|
--Fred

I know I can also use relationships to do some of this. But I wonder what is easiest to see and manipulate?