It's a tough search that you are facing! I see you are also trying some other venues on the Internet. A suggestion: calculate nine months back from your Dad's birthday, and try to find out which German units were located in Scheveningen/The Hague at that time. Maybe that could narrow your search. At www.volksbund.de you can search the files of German deceased WW2 soldiers, though my quick search didn't reveal his name. Which does not prove he survived the war, hundreds of thousands German soldiers were buried unidentified.