If what is happening is asking the public to come along and have go at dancing then IMHO there should be a number of quality, well-rehearsed dancers there along with quality well-rehearsed musicians who both (dancers and musicians) know what they are doing.

But this was an appeal for dancers and musicians to come and join in an unrehearsed public performance - even if the public are being asked to join in at some point. Are they being asked to join in immediately? Is there a show first and then they are asked to join in after a demonstration - which seems to me to be the most likely. Who then does the show? Have they rehearsed?

Otherwise it seems to me that you have the partially-sighted leading the blind!!