Having run a successful Folk Club, I never had any situation where someone like Flora was not allowed a spot of her own just because she backed someone on their turn. In fact that was a fairly occasional occurance. If we take two numbers as standard then if you wish to invite someone up to accompany you on your spot hey that's fine. And would be perfectly happy with them sill having their own spot. I did once encounter a situationn where an instrumentalist took advantage of the situation and started popping up 4 or 5 times in the evening to back various others. But a quiet word soon put a stop to that. The protocol at Singers nights/open Mic nights is fairly straight forward, a half decent MC will try to ensure each performer get's an equal share as time allows, and performers in turn should respect that by i.e try to keep a two song spot to around 8-10 minutes, If you must do one very long song ( I had once chap do 26 verses once!) then make the next a quick one, try to be tuned up before you get up, 10 mins allows time to have some chat but please no speeches! And just enjoy yourself