Complex sentence: The series also starred William Frawley as the boy's live-in maternal grandfather, Bub, who was replaced in 1965 by William Demarest due Frawley's health issues.
Split into simpler sentences: The series also starred William Frawley as the boy's live-in maternal grandfather, Bub. Frawley, was replaced in 1965 by William Demarest due to health issues.