Willem married Polanen Petel Irma Ledya Augusta on 11 Sep 1934 in Surakarta, Indonesia. Irma was born on 27 May 1894 in Klaten, Indonesia; died on 18 Mar 1982 in Den Haag. [Group Sheet]

Willem married Sytsma Louiza Jozefina Margaretha on 24 Dec 1959 (civil) in Den Haag. Louiza (daughter of Sytsma Gerard Herman Abraham and Romanesko Louiza Johanna Christina Cornelia) was born on 10 Nov 1913 in Batavia, Indonesia; died on 4 May 2001 in Den Haag. [Group Sheet]