P.D.Q. Bach. Children, I am serious. This theme is a minefield. A musician – a scientist and professor – just "invented" a twenty-first Bach son. Who created music (... of course, our professor did) and has its own biography. Some find that funny, some are confused, some find it ... just silly.
My job here – at least I think so – is to tell you about and to suggest you "sail around that trap". If you learned truckloads about Johann Sebastian Bach, if you are interested in the Bach genealogy and finally you are deep enough into the subject, then – not earlier – check about P.D.Q. Bach.
I find the whole Bach universe so confusing, that it doesn't need more artificial ballyhoo. So, if the term P.D.Q. Bach comes up, you are aware: Stay away. Do not google.
Advertisement = Promotion = Commercial
99 Music Calendars, Composers Calendars and Bach Calendars
End of Commercial = Adverstisement = Promotion