Complex sentence: Gilmore pianos began production in 1904 as a private label for a retail customer in Philadelphia, the customer being Gustave Herzberg (1835--1924), father of Edward Herzberg (1870--1931), who ran the piano department at the Snellenburg Store.
Split into simpler sentences: Gilmore pianos began production in 1904 as a private label for a retail customer in Philadelphia. They were originally produced for Gustave Herzberg (1835--1924), father of Edward Herzberg (1870--1931), who ran the piano department at the Snellenburg Store.