Family #24 in the 1775 Grimm census.
1775 Grimm Census 
He may be a match with Heinrich Friesorger, from family #2 in the 1798 census and family #78 in the 1834 census.
The Friesorger name does not appear in any Volga German immigration record, nor in any other village records in the 1798 Volga village censuses, nor in the 1775 Grimm census. For a time I was focused on this surname being co-mingled with Fritzle or Fritzler, but it also seems possible that Frizol morphed into Friesorger with the L changing to an R and the GER ending added to the name.
Heinrich Frizol does not appear in any immigration records, although his name may have be accidentally omitted from these records or included under another surname, as in the surname of a relative. He appears in the 1775 census in his sister's family, the Linden/Linde family. In this record he is the husband of a woman named Elisabeth, who was 16 years old at the time of the 1775 census. The couple is never mentioned again in Grimm census records, nor do they appear in any other Volga village record.
Coincidentally, his older sister Maria Sybilla Frizol Linden/Linde had a daughter named Elisabeth who would have been 16 years old in 1775. She is said to have married Heinrich Friesorger, who is roughly the same age as Heinrich Frizol. The name is probably misspelled as Friesonger in the 1798 census, but spelled as Friesorger in all subsequent census records. Heinrich Friesorger does not appear in Grimm before the 1798 census, but he and/or his descendants appear in all subsequent Grimm census records. The name in this form survives to descendants who immigrated to the United States in the early 1900s and eventually settled in the midwest.
It's possible that Heinrich Frizol, brother of Maria Sybilla, and Heinrich Friesorger are the same person.
Because of the 20+ year gap between Maria Sybilla and her younger brother Heinrich, it's also possible that Heinrich was her half brother, not a full brother. The same surname indicates that they at least at the same father but may have had different mothers.
If these two men are the same person, then it means that Maria Sybilla's daughter Elisabeth Linden/Linde married her maternal uncle, Heinrich Frizol/Friesorger. This union represents an avuncular marriage, a legitimate practice in historical Europe, as well as in modern-day Russia. 
This theory cannot be easily proven unless through early marriage records. Although there are numerous male Friesorger descendants, there are no other known Frizol descendants, nor are there any male Linden/Linde descendants. Female Linden/Linde descendants would be scattered amongst other surnames.
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