The band that GF is referring to is Pete The Hat's friends Unity & Division and only 2 of them go to the camp - BUT they have some friends down as well and they like to join in. The MC must take control if he/she thinks unfair hogging is occurring. I've had some people who tried what I call the "Stacking" technique at my club. What will happen is two will turn up and ask for a spot at 9pm then somebody else will turn up and ask for a spot at 9.10pm then another couple will turn up and ask for a spot at 9.20. At 9pm the first couple take the stage and then invite the other 3 to join them and before you can say Jack Robinson you end up with a 5 piece jazz band that nobody else will book playing a 30min+ set. Luckily I knew the local jazz scene and sussed them out gave all five one 15 minute slot.