I'm a professional musician, and I wouldn't think of forcing a lot of obviously uninterested family members into carol-singing and breathless adoration of child performers, no matter how talented. All too often, it's unutterably boring for everyone else. (Listening to a tyro violinist screeching out a halting version of "Silent Night"... yeah, no fun for anyone except possibly the stars-in-their-eyes parents.)
The word "no" is a complete sentence. It can be said in so many ways. Even cheerfully--and it takes the wind out of their sails if that's all that's said, without JADE. As long as one never expands on it further or loses one's cool, there really is no way to refute it.