There are 15 non-party member masters you can invite. Party members also count as masters at the altar at Rok's fort, bringing the total to 21. There are some NPCs that have additional scenes, too.
Oooh, does the npc from akoh village count as inviteable?
The one who wants money? He's a master to invite.
No, the other guy that made us lick his tailhole
That one only has the tailhole scene. The merc can join, though.
