Family #90 in the 1775 Grimm census.
Family #73 in the 1798 Grimm census.
Family #162 in the 1834 Grimm census.
Maria Elisabeth Braun was born in 1768 in Grimm, Russia, the daughter of Andreas and Dorothea Braun.
1775 Grimm Census 
Note that by 1775, both her parents had passed away and she lived with her step-father, Andreas Getz, and his second wife, Elisabeth Schutz.
1798 Grimm Census 
The 1798 census identifies Elisabeth as Eva Elisabeth Braun, the widowed mother of Elisabeth Braun Krug. That said, Eva Elisabeth's married surname was never actually Braun, it was Getz. She was a double step mother to Elisabeth, since she wasn't her mother and was never married to her father, only her step-father. But she would have been the only mother young Elisabeth would have remembered, so it is not surprising the women were close. Even after the death of her husband, Maria Elisabeth's step-father Andreas Getz, Eva Elisabeth continued to live with her "step" daughter. It was probably easier for the Krugs to identify Maria Elisabeth's "step" mother as a Braun than to try to explain the complicated family relationship to the census taker.
When comparing her ages in the 1798 and 1834 census records, she is the same age as her husband in 1798, and she is 11 years younger than him in 1834. Unless this is a typo, this is not a simple error. It appears that Maria Elisabeth of the 1834 census is a different person, one much younger than Matthias Krug's first wife. I am separating them into two people.
All of the children in the 1798 census belong to Elisabeth; that much is certain. There are two additional children in the 1834 census: Johannes, born in 1812 and Maria Magdalena, born in 1815. Neither of them are listed as belonging to Matthias' first wife, so I am identifying with as the children of his second wife, Maria Elisabeth. She would have been 37 years old at the birth of her youngest child. If I learn otherwise, I will update the profiles accordingly. Here is what the 1834 census looks like.
1834 Grimm Census 
When searching the census records, there is only one match for second wife Maria Elisabeth in the 1798 census:
To sum up:
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