Maybe J.S. Bach’s most famous child composer was his son, Carl Philipp Emanuel Bach, born in Weimar, Germany on March 8, 1714.
C.P.E. Bach [March 8, 1714 – Dec. 14, 1788]

From Carl Philipp Emanuel Bach – Wikipedia: ” … was a German Classical Period musician and composer, the fifth child and second surviving son of Johann Sebastian Bach and Maria Barbara Bach.
C. P. E. Bach was an influential composer working at a time of transition [Rococo Period] between his father’s Baroque style and the Classical style that followed it.”
Please turn up the volume and enjoy some great compositions from C.P.E. Bach.
C.P.E. Bach: Symphony #1 in D Major:
C.P.E. Bach: Harpsichord Concerto in F Major:
C.P.E. Bach: Solfeggietto in C minor for Keyboard:
C.P.E. Bach: Flute Concerto in G Major:
Happy Birthday #309 C.P.E. Bach!