Maybe your Schlosser relatives attended the same Shul my Jewish ancestors from Darmstadt area attended. Their surname was Kick.
My Jewish relatives are SCHMIDT also. We wear the name proudly. It may be German but OUR branch is GERMAN JEWISH. We are a separate category of Jew. It was German Jews who founded Broadway, Hollywood and the great retailing empires of the USA.
We were the educated Jews, the cultured Jews who gave the world Reform Judaism. So just because a name may have "German" origins, it doesn't mean that we aren't JEWISH. IN fact, Askenazic Jews--usually from Russia and Eastern Europe as portrayed in Fiddler on the Roof are NOT necessarily German Jews per se.