Banishment back to hell (pg 26) notes something interesting:
- if the demon that leads/commands them (typically a Greater Demon) is banished to Hades, ALL the Lesser and Sub-Demons that served him, even
those outside the circle, get no saving throw and are banished
I guess what I'm wondering here is, how would we go about establishing that link?
Unless there's some actual act to designate that relationship (maybe a greater demon who can summon a lesser demon using a spell or natural ability) what if demons are just considered informally working together to avoid this kind of mystical mass-deportation?
IE a demon lord sends 100 alu "hey listen to what this Archfiend says, but he's not technically your leader, I am" to avoid the problem of the alu getting deported when the archfiend gets trapped in the circle.