Complex sentence: In 1929, Reinhardt's estranged wife, Florine, gave birth to a son, Henri "Lousson" Reinhardt, who grew up with the surname of his mother's new husband, Baumgartner.
Split into simpler sentences: In 1929, his wife gave birth to a son, Henri "Lousson" Reinhardt. His son later took the the surname of his mother's new husband, Baumgartner.