I guess I'm lucky that our session has always been respectful of people who join in whether with song or instrument, and many sing and play both. We've been meeting since about 1994 and have successfully kept the core group of people involved with many great experiences of people who join in over the years. There is no formal club, no leader, no written rules, no member/non-member status, no nazi controls. We'll move from tunes to songs and everyone seems to have a good time, whether solos, group tunes, solo songs or group songs. It's all about enjoying making music. It is kept mostly to Irish or Scottish music, but if someone adds in an American or English or Canadian or French or Welsh or Australian tune or song, it is respected and enjoyed.