Is your Themann lutheran (northern of the province Oldenburg) or catholic?
If they is catholic then could be from the area of Vechta, Lutten, Hausstette or Steinfeld.
The Steinfeld curch register show this:
born 01.March 1848 in Steinfeld, parents: Henrich Themann and Anna Maria Wieferig
it shows not a Franziska.
Gedding is a name of Westphalia.
Werner