When playing in Pinks pub, the random NPC's that enter might join you for a game of Yenten if you sit next to them and join the game.
I guess if you were sitting right next to them and started the game, they could join after you do. Could be an alright idea.
Hm, had another thought, that maybe you talk to them, and have a 'yenten' option to invite them to play. So, different NPC's might accept or decline as well.