Katharina Margaretha was born after the 1798 census and married before the 1834 census. This means she was not captured in a census with her biological parents. Unless we find a descendant who has detailed private records, we will probably never know her last name at birth.
Identifying the maternal haplogroup of Katharina Margaretha's female descendants could help narrow down her maternal ancestry.
Great Grandchild #4 Christina Margaretha, age 1 year 6 months
Grandchild #2 Johann Heinrich, age 29
Wife of Grandchild #2 Elisabeth, age 27
Great Grandchild #5 Katharina Elisabeth, age 6 years 6 months
Grandchild #3 Georg Peter, age 25
Wife of Grandchild #3 Eva Katharina, age 23
Great Grandchild #6 Johann Peter, age 2
Great Grandchild #7 Johann Heinrich, age 6 months
Grandchild #4 Katharina Margaretha, age 23, unmarried
Grandchild #5 Georg Heinrich, age 22
Wife of Grandchild #5 Katharina Margaretha, age 21
Great Grandchild #8 Georg Jakob, age 1 year 6 months
Great Grandchild #9 Johann Heinrich, age 6 weeks
Grandchild #6 Christian Jakob, age 17, unmarried
↑1834 Census of Grimm in the District of Saratov, Russia, dated 2 February 1835; Translated by Brent Mai, Concordia University, Portland, Oregon; Published by Dynasty Publishing, Beaverton, OR, USA; Published 2011; page 43, family #139.