David Koopman was a son of Joel Koopman and Dientje de Vries, both born at Leeuwarden, who were married in Amsterdam on 20 August 1885. David Koopman was the eldest of a twin. His twinbrother was Bernard Koopman, who was married to Sara Saphier. David Koopman was an upholsterer and unmarried.
City Archive of Amsterdam, archive card of David Koopman and Bernard Koopman, family registration card of Joel Koopman and website www.wiewaswie.nl.