the Radiators made the family move so they could do their show?
The band has no say in how the bar books its schedule, so certainly not. The band has no control whatsoever over "making the family move" and I'm quite certain they would have been very pleased to mix the two events, if such a choice was theirs to make (in fact, Reggie says exactly that, in the quote above).
I believe the family decided a while ago to move it to a larger place, and soon thereafter, the bar booked the Radiators. Seems like the party needed more room for props, decoration, photographs and TV, etc.