This week, a group called LitvakSIG released new data for Svencionys, where Ari's Gurvich (Hurwitz) ancestors come from. The spreadsheet I received was a Revision List from 1816 and 1818. A Revision List is a type of census, collected to find the people who needed to pay taxes, and they are some of the best records to show who is living in each household, with their names, ages, occupations and other notes (several are noted as being "on the run" or missing).
At this time, Jews did not all have surnames, so you sometimes have to look at the father's name to help you identify families. The two surnames I knew I was looking for in Svencionys were Gurvich and Schnaiderovich, so I filtered the spreadsheet on those names.
At registration no. 166, I found the household of Ari's 7x great-grandfather, Berko Gurvich. The 1818 Revision List told me that he was the head of the household, aged 40, putting his date of birth at 1778. This was new information. It also showed his son, Movsha, aged 15 (this is Ari's 6x great-grandfather). And it listed Berko's wife, Bushke, aged 35. There were no other children listed in the household.
But the new information was that Bushke's father was called Gershen. Unfortunately we don't know Bushke's surname, but we do now know tthat she was the daughter of Gershen, so Gershen would have been born in about 1760.
Ari, this is how you are related to Gershen: