Lol - young Mozart had his sister Nannerl when they were on trip with father Leopold, performing before European aristocracy and royalty.
As for the legend with the nose, there are, indeed, several versions, also one, in which, as a pupil, he challenged Haydn.
But that reminds me of several "keybord 4-hand" compositions, and performances by Brigitte Engerer and Boris Berezovsky, for instance: Hungarian Rhapsody - Liszt
(unfortunately, I couldn't find a short video on which they play Mozart).
and a funny one (Lavignac - Le grand galop pour huit mains)