Kerstin, Perhaps this will help. American Historical Society of Germans from Russia help persons in all countries find relatives. Especially Germans who went to Russia, then came to America, or back to Germany with the fall of the Berlin Wall. firstname.lastname@example.org
They have this record as follows: Madlin or Catharina Hartung, daughter of Heinrick and Catharina Margaretha Hartung from Frank. Heinrich was son of Gottlieb Hartung.
I suggest you check for Hartung records in Frank. Best wishes.