The goal of this project is to explore the various relationships between the Oppenheim and/or Oppenheimer families worldwide. Prior to the 19th Century, many Ashkenazi families did not adopt surnames; moreover, it was not uncommon for sons to take surnames from their maternal side. Consequently, I would expect there to be some quite distinct family lines with the same surname, as well as very closely related lines bearing different surnames.

Per "A Dictionary of Jewish Surnames from the Russian Empire, Revised Edition," variations included Oppengejm, Appengejm, Ofengejm, Opengejm, Gopengejm, Gopenkhaim.