Well, I have not had time to read ALL of this thread, but if it has not been said, the most important factor is :



      UNACCOMPANIED MEANS   UNACCOMPANIED.


I sing unaccompanied, and if someone starts to play, I sit down.
End of story.

the ONLY time a musician should "help out" is if s/he is ACTUALLY ASKED TO DO SO

Jo-Jo