Since I see everyone is liking the idea with collaborations,
The ones that do collaborate, would it be better if those characters you collaborate with, that will be your "division/group" you break off with into the different tunnels of the catacombs? I figured people would break off with a group or go alone into their own path of the catacombs at some point. It's a big premise to cover.
Just throwing out suggestions to make it easier or flexible~