Johann Jacob Mahr (son of Johann Peter Mahr from Wildsachsen) married Eleonora Philippina Dorothea Winden (daughter of Georg Winden from Massenheim) on 25 April 1747. Johann Jacob and Eleonora Philippina Dorothea had ten children, all born and baptized in Wildsachsen on the following dates: twins Johann Philipp and Anna Margaretha, born and baptized on 10 April 1748; Catharina Margaretha, born 9 April, baptized 11 April 1750 (died 5 March 1752); Christina Elisabetha, born 15 November, baptized 18 November 1751; Catharina Margaretha, born and baptized 14 April 1753; Maria Elisabetha, born 20 September, baptized 22 September 1754 (died 10 March 1756); Catharina Margaretha, born 20 February, baptized 22 February 1757; Christina Margaretha, born 2 February, baptized 4 February 1759; Johann Peter, born 13 February, baptized 16 February 1761; and Johann Jacob, born 11 May, baptized 13 May 1764.
Eleonora Philippina Dorothea died on 21 October and was buried on 23 October 1765. On 10 June 1766, Johann Jacob married Maria Appolonia Fraund (daughter of Gerhard Fraund from Niederseelbach).
The Mahr family was recruited to become Russian colonists by Baron Caneau de Beauregard. Johann Jacob, Maria Appolonia, and their eight children are recorded on a list of colonists recruited during 1766, but who had not yet been transported to Russia in 1767. The Mahr family is among the few families on the list who can be identified in later documents as settling in the Volga German colonies. They are not reported on the 1767 Census, so they must have arrived at some point after that Census was taken.
The Mahr children are reported in the following households on the 1798 Census: Johann Peter Mahr in Walter Household #1; Johann Jacob Mahr in Walter Household #73; Anna Catharina Mahr in Kolb Household #10 (married to Nicolaus Koch); Anna Margaretha Mahr in Walter Household #38 (married to Conrad Dietz); and Christina Elisabeth in Huck Household #76 (married to Justus Luther). The Walter 1798 Census also includes three Mahr individuals in Household #115: Catharina, age 22; Nicolaus, age 17; and Johann Heinrich, age 14. They are described as Jacobina Schmidt's children from her first husband Jacob Mahr. It is unclear based on the available information if the senior Jacob Mahr married for a third time and these are his children, or if there is a mistake in the census and these are actually children of his son Johann Philip.
- Parish records of Medenbach and Wildsachsen on Archion.de.
- Idt, Andreas and Rauschenbach, Georg. Die "Berufer" Abenteuer der Aufklärung in Katharinas II. Kolonisierungsprojekt (Moscow: 2019). p. 177
- Mai, Brent Alan. 1798 Census of the German Colonies along the Volga: Economy, Population, and Agriculture (Lincoln, NE: American Historical Society of Germans from Russia, 1999): Vol 1, pp. 512 and 607, Vol. 2, pp. 994, 999, 1004, 1010.