Joseph van Os was a son of Nathan van Os and Keetje Weesel. He was married in Amsterdam on 12 December 1906 to the widow of Isaac de Vries, Vogeline de Rosa. The couple had six children together: Nathan, Wilhelmina - she survived the Holocauste - Neftalie, and the sons who lived at the same address as their parents: Hartog, Andries en Salomon. Joseph was a vendor on the Albert Cuypstraat market. T…