Sub-factions and allegiances

The rule

An army picks one sub-faction, allegiance, or detachment, and that choice unlocks its own traits, artefacts, or special units.

The structure

Give the catalogue a single shared "Allegiance" entry, set min 1, max 1 in the force, so every army must choose exactly one. Inside it put a group holding one entry per sub-faction.

Hang the sub-faction-specific content off that choice:

• Keep each set of traits, artefacts, or spells in its own container group.
• Hide each container by default and reveal it with a modifier whose condition tests that its sub-faction is the one selected.

Because the containers are nested under the allegiance choice, tick "and all child selections" on those conditions.

Notes

• Define the sub-faction choice once and link to it where needed, rather than repeating the list.
• If a sub-faction changes which battlefield role a unit takes, drive that with a modifier on the unit rather than duplicating the unit; see Army-wide limits and Scope & Context for the conditions involved.
• Large systems keep shared sub-faction content in a separate library catalogue the faction files link to, which keeps each file smaller.