Dances With Balrog is absent from the Alliance meeting.

There's a Mercedes NPC in the game's data that is apparently unused, possibly meant to be used at the meeting.

Also to add to my previous post, Phantom and Luminous get Will of the Alliance from just talking with Cygnus, they don't even get the cutscene + the meeting room.

Not unused, IIRC she just randomly shows up at Six Path Crossing if you're a Demon Slayer.