This is how close I live to Groat Schormer (actually Grootschermer, the place Maria Elizabeth Stuurman came from) ; 10 km !!

You mentioned Gross Sommerda in Thuringen near Oumar.

Thüringen is a state in Germany and what you call Oumar is Weimar (see maps). I remember my cousin telling me Lodewijk came from Weimar so that’s more than likely to be true.

I haven’t figured out Gross Sommerda yet, though I know it must be a place near Weimar. It will be spelled Groß, cause those Germans spell ss with this special character ß.

I found a very interesting URL when I was looking for Groß Sommerda (or something similar). The URL is http://www.geocities.com/Heartland/Prairie/1843/home.html

This seems to have a surname and queries board for Thuringen.  Very interesting!!  We really need to get in to that!