She was married three times, first to Lord David Douglas-Hamilton. He was a squadron leader in the Royal Air Force, was killed in 1944 when his damaged airplane crashed following enemy action over France. In 1950, Stack married the surgeon Ally Albers in South Africa. Albers died in a climbing accident in 1951, while climbing Table Mountain accompanied by his wife. In 1964, she married Brian Power, a barrister, who died in 2008.