Vedder family in mid-late 1700s NY

The NY census of 1855 states shows that David Scott 's mother-in-law was named Nancy Vedder, presumably she was the mother of his wife Sarah Scott.

https://www.familysearch.org/ark:/61903/3:1:33S7-LBR8-V66?i=10&...

The age of Nancy Vedder given in 1855 is 75 making her DOB c.1780

There is no place of origin given for Nancy but given the name Vedder and Sarah's stated origin of Schenectady it seems highly likely that Nancy too was from Schenectady.

I have not found this family in the 1860 census.
The 1870 census is where things start to mesh/fall apart, depending on your perspective.

https://www.myheritage.com/research/record-10128-146379966/sarah-ve...

This time we have David Scott living with his wife, Sarah, and youngest son, Charles, and an elderly lady named Sarah Vedder who's relationship to David is not explained.

Sarah (Nancy?) Vedder's age in 1870 is listed as 81, but again no record of her place of origin, this would make her DOB c.1789.

Now the interesting point to note here is that the other Nancy Annatje Vedder was baptised in Schenectady in 1789:

1789 Nov 08; Frans Van De Bogart Vedder, Lena Bancker; Annatie (b), m. John Newkirk

So we have two records of David Scott living with a elderly lady from the Vedder family. The name in one record suggests a match to the older Vedder family while the DOB of the other record also suggests a link to the very same family.

Unfortunately the Vedder family/families in Schenectady aren't that small but so far i have found only one Nancy and no Sarahs baptised in the 1780s.

Dang, it occurs to me now that if Annatie "Nancy" Vedder married John Newkirk as per the above record from Schenectady baptisms - Pearson's Genealogies then there is no way her daughter could be named Sarah Vedder, she would be Sarah Newkirk.

Likewise, if David Scott's mother-in-law was named Vedder in 1855 it is very unlikely that she was baptised a Vedder.

I need to read back over this again, sometimes writing things out helps.

I found the family of David Scott in the 1860 census but he has no elderly woman living with him at all.
I think I found Sarah Vedder in the 1860 census, she is living with a sister(?).
My hypothesis now is that Nancy Vedder (1780-c1856) was the mother of Sarah Scott (Vedder) and that Sarah Vedder (1789-c1871) was the younger Sarah's paternal spinster aunt.

So I am now looking for Mr X Vedder married to Nancy Vedder (?) with a sister Sarah Vedder and a daughter named Sarah Vedder, easy!