Molinaro joined the cast in Season 4 after Pat Morita, who played Arnold, left after the end of the third season (in the last episode "Arnold Gets Married"). Subsequently, Molinaro also played Al's twin brother priest Father Anthony Delvecchio.
After Pat Morita departed from the cast in Season 3's finale ("Arnold Gets Married"), Molinaro joined the show for Season 4 as a new character. He also played Al's twin brother, Father Anthony Delvecchio.