Hi Chris, Yes Rosa Elizabeth Ferguson was Joseph's common law wife. They had four children together - Minnie (yes another one!), Lily, Olga and Thelma. Minnie was born in Tasmania, the other girls in Sydney. Rosa was born in Tasmania, her brother was Albert. Rosa died in Sydney in 1937. She had married and adopted another first name, she is buried as Alice Jean Foulds. There are quite a lot of descendants of Joseph who get together regularly. My family is descended from Minnie. Where do you fit in?
P.S. Although Joseph was prosecuted for slave trading, he was acquitted and it was very controversial at the time, so hardly fair to refer to him as 'Joseph Vos Slave Trader'