John and Mariah CLOSS are my 3rd great grandfather and grandmother.I've seen the census you refer to and have wondered about that line too.I can't add too much but maybe a bit.John was born 29 Jul 1804.
The 1880 census states that Betsy is the niece of John Closs.That would suggest she is the daughter of one of John's brothers or sisters.
My research has found that John had at least 2 brothers, Henryborn 26 Apr 1813 in Montgomery Cty, and George born 11 Dec 1815 in Montgomery Cty.I don't know any more about these lines although I have come across a Henry Closs family in Jefferson Cty that maybe related.In 1855, John Henry Closs below had a son Henry Monroe Closs not to be confused with the aforementioned Henry.Also,John and Mariah had a son named Georgeborn abt 1833 not to be confused with the George of 1815.
John had at least 2 sisters, Catherine (Polly) born 1 June 1801 in Montgomery Cty and Lucinda Hellen born 16 Feb 1818 in Montgomery Cty.
Catherine married Peter YORDON and had Betsy Ann Yordon and 7 other children.John and Mariah (aka Susan) had John Henry CLOSS and 10 other childern.Besty Ann married John Henry.These are my 2nd Great grandfather and grandmother.
Lucinda married John FRAIZER and had at least 2 sons, George born 11 Mar 1839 and William born 18 Jan 1844.This family resided around the Spragueville area on the county line between Jefferson and St. Lawrence County.Lucinda died abt 16 May 1876 and is buried in the Spragueville Cemetry.
This is about all I have thatmay help.There is a time gap between John in 1804 and Henry in 1813 suggesting additional siblings are possible but I don't know who they are.
Niece Betsy could have been a child of Henry, George, or Lucinda.I have the children of Catherine down pretty well and she is not in that line.