Complex sentence: The Keatons consider preschool for the child in an episode aired 13 months later; the next season, which began September 25,1986, Brian Bonsall was cast in the role at the age of four.
Split into simpler sentences: The Keatons consider preschool for the child in an episode, which was aired 13 months later. However, in the next season, which began on September 25,1986, Brian Bonsall was cast in the role at the age of four.