<Li> Don Grady, Robert "Robbie" Douglas (1960--1971) </Li> <Li> Stanley Livingston, Richard "Chip" Douglas (1960--1972) </Li> <Li> Barry Livingston, Ernest "Ernie" Thompson / Douglas (1963--1972) </Li> <Li> Meredith MacRae, Sally Ann Morrison Douglas (1963--1965) </Li>

When did ernie first appear on my three sons