Complex sentence: Peter Marshall was born as Ralph Pierre LaCock to a show business family, moving to New York City at the age of 12 following his father's death to be with his mother, an aspiring costume designer and later the president of the Motion Picture Mothers.
Split into simpler sentences: Peter Marshall was born as Ralph Pierre LaCock to a show business family. Following his father's death, he moved to New York City at the age of 12 to be with his mother, an aspiring costume designer and later the president of the Motion Picture Mothers.