Judith Korper married 29 July 1942 in Amsterdam to Jacob van Bever, a son of Hartog van Bever and Schoontje Schelvis. City Archive of Amsterdam, archive card of Judith Korper.
Sophia Vreeland was the widow of Simon Korper (08-12-1892/29-12-1934). She also had a son Philip. Stadsarchief Amsterdam, archiefkaart Philip Korper
In addition, a Jokos file (number 2807) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.