Hello Mona -
I do not have the Uelzen book but I recently had Dieter Boe do some research for me on my Thiemann/Tiemann/Timann family from Melzingen - the church records for Melzingen are at Ebstorf. The information he sent me goes back to before 1500. My Dorothea Thiemann's mother was Catharine Maria Dorothea Rieckmann! There was a great deal more information than I really wanted since Dorothea is only related by marriage to my Ludwig Degener.
I wonder if this Rieckmann family could be related to yours?
When Dieter did some work for me, he traced the WOLLE line. My ggrandmother was WOLLE who married a Rieckmann. But he didn't trace the Rieckmann. So I can't tell you if I connect to a Degenger. Maybe after I get the book, we'll be able to tell.
Did you Thiemann go to Grand Island,Nebraska? I know there are some who did. I find this fascinating because my ggrandparents settled only about 35 miles west of Grand Island, after living several years in Will County, Illinois.
I'm also fascinated that you have a Catharine Maria Dorothea. Those 3 names + Anna and Elisabeth seem to be almost the only names they used for females. Males seem to be Heinrich and Christoph and Wilhelm. Over and over and over again!