My great-grandfather was Johann Dottermann. He came to the U.S. in 1910 from Vojtek, which was then in the Kingdom of Hungary, and is now in Romania. My great-grandmother, Anna Dottermann, came with Johann. Ellis Island records a 15-year old boy named Thomas Dottermann arriving on the same day on the same ship. I assume he is a relative of Johann & Anna, probably a son.
From 1909-1941, my grandmother corresponded with relatives still living in Voytek, but totally lost track of the family after WWII.
I have no idea of my Voytek family had relatives in Germany, so I can't say that we are related. I have heard no family stories of relatives in Germany.
I wonder why your family moved from Germany to Romania. That seems an odd move following WWI.