Question: who played chip douglas on my three sons
Answer: To keep the show 's title plausible , the show 's head writer , George Tibbles , fashioned a three - part story arc in which an orphaned friend of youngest brother Richard ( Chip , played by Stanley Livingston ) , Ernie Thompson ( played by his real - life brother , Barry Livingston ) , awaits adoption when his current foster parents are transferred to the Orient .