It's nice to hear from you. Since I posted my reply to your brother, I've learned a little bit more about Seth. Turns out he did not move his family to Durham, New York, after living in Richmond. According to deed records and the census, he officially lived in Richmond until moving to Berkshire, New York (and that was around 1810, not 1812 as I previously stated). He owned property in the Richmond/Pittsfield, Massachusetts area and sold it in 1810, and his address on those deeds is given as Berkshire. But he definitely was in Durham, NY, possibly living with a brother-in-law, as he sold lumber to a local businessman, and he also is listed as one of the highway supervisors for the town during its first years of development.
As for Content's children's tombstones, this may solve a puzzle, as we were aware several of her children died from some kind of disease, but their tomstones could not be found where her husband is buried in Speedsville, Tompkins County, NY near where they lived in Berkshire. We had assumed they died here before Content moved out to Michigan, but it looks like their deaths must have occured after the move. Can you give me the children's names and dates?
By the way, one of Seth's descendents apparently made a silhouette of him. It is on display in the Tioga County Historical Museum and I took some digital photos of the silhouette and the plaque it is mounted on a few years ago. I can send them to you, if you're interested.
We still have found nothing definitive on Seth's mother's maiden name nor her last husband (Jones), nor on his grandfather's and grandmother's origins.