Isidore Nathan Philip de Heer was married to Rozetta Polak. He was a stamp dealer and Rozetta was a school teacher. They both attended the wedding of their daughter Evalida Betsy de Heer to Salomon Brandon. The marriage was performed at Westerbork transit camp on 30 april 1943. The parents signed the marriage certificate.
Record of marriage certificates of the Westerbork municipality, currently at the archives of Gemeente Midden-Drenthe in Beilen
In addition, a Jokos file (number 53716) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.