Complex sentence: He was the second son of Philip E. Buehler and Mary Froelich, and was the middle child between his older brother, Hugo Buehler, and younger sister, Wilma Buehler.
Split into simpler sentences: He was the second son of Philip E. Buehler and Mary Froelich. He had an older brother, Hugo Buehler, and a younger sister, Wilma Buehler.