Hello Johan Dusseldorf has a municipal archive (Stadtarchiv). You can contact them via email and I think they would offer you to go through the documents (birth, marriage etc.), if you have the names and dates etc.: Stadtarchiv Düsseldorf Worringer Straße 140 D-40213 Düsseldorf Germany Tel: +49 211-89-95737 Fax: +49 211-89-29155 E-mail: firstname.lastname@example.org If this is not helpful, you can contact the catholic churches in Dusseldorf additionally. Good luck, Mirjana.