Family #74 in the 1775 Grimm census.
Family #116 in the 1798 Grimm census.
Eva Bechtold was born about 1735 to parents who have not yet been confirmed. Just prior to immigrating to Russia in 1766, she was living in the Isenburg area of what is now Germany. She may have been born in that area, or moved there after her marriage to second husband Balthasar Rudolph.
Her first husband was identified by the surname given to his daughter in the 1775 Grimm census: Lusmar. That is almost certainly a misspelling of the surname. A brief search of German records on FamilySearch.org shows the following possibilities for spelling that surname:
Whatever the spelling, there is no online record of Eva's marriage to a man with any of those surnames. Their marriage took place between 1752 and 1758, and daughter Catharina was born in 1759. Mr. Lusmar passed away at some point before 1766, at which time it was documented that she was married to Balthasar Rudolph in immigration records.
Eva married first husband Mr. Lusmar by 1758 and their daughter Catharina was born in 1759. The date of Mr. Lusmar's death is not known. If Mr. Lusmar died between 1759 and 1761, Eva could have married Balthasar and had son Johann Konrad in 1762. If Mr. Lusmar died between 1762 and 1765, Johann Konrad was the son of Balthasar Rudolph's unknown first wife who must have also passed away. A later census suggests Eva was Johann Konrad's stepmother, indicating that her marriage to Balthasar took place after 1762. The suggestion comes in the form of naming daughter Catharina Lusmar as Balthasar's stepdaughter in the 1775 census, even though there was no documentation of this kind of a relationship in the 1766 Kulberg Reports.
Despite the fact that Germans had a reputation for being good, hard workers, many people struggled to survive. In addition to war and famine, the economic conditions were adversely affected by high taxes and burdensome tithing expected by the local Church. When Catherine the Great issued her manifesto, an invitation to people who in the ravaged areas of Germany to move to Russia with many personal and financial incentives, Eva and Balthasar decided to immigrate.  Johann Konrad was four years younger than Catharina, according to this record. 
While it appears that Eva is his mother, it may be that she was actually his stepmother, based on 1775 Grimm Census details. This would mean that Balthasar Rudolph was also married once before and had Johann Konrad with his unnamed first wife.
The Rudolph family departed from Rewal on the Pink Novaya Dvinka, a small, flat-bottomed ship with a narrow stern, typically square rigged and used to sail short distances and/or in shallow waters.  They arrived in Russia on 30 May 1766. 
Immigrants waited until the following spring to make their final journey to the Volga River colonies, and censuses were taken by August 1767. The Rudolphs were not listed in the first Grimm census. They may have settled temporarily in another village before moving to Grimm, but that village has not yet been identified. The family is first listed in the 1775 Grimm census.
1775 Grimm Census 
The 1798 census shows that her daughter Katharina was no longer living with the family. She had most likely married and was living in a different household. The census also reveals that she had another son born in 1775, but after the 1775 census was taken. His name was Andreas Jakob Rudolph. Son Heinrich was living with the Pikus family (#57), and daughter Carolina Sabina married Gottlieb Makarovka from Merkel and moved away to live with his family. 
1798 Grimm Census 
Eva Bechtold Rudolph is not listed in the 1834 census, and it is likely that she had passed away before that year. Had she survived, she would have been about 99 years old.
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