Gertrud Marcus was first married to Sally Winter. After they got divorced, she married Frits Seelenfreund in 1931. They got divorced in 1939. Stadsarchief Amsterdam; Archiefkaart van Gertrud Marcus
Fritz Seelenfreund managed to flee to Shanghai before the war. In the Red Cross Archives many documents testify to the fact that Fritz tried to apply for Japanese citizenship both for himself and the children. (File number 119.483)