Some genealogies have this Stephen as a son of John b.1770, brother of Eliphalet. However, if this Stephen was really born in 1780, that particular John could not have been his father (needs more research). Also, if he really was born in Ilion, NY, do we know that John & Mary (of RI) were living there?
The cemetery record states that Stephen was born in Washington County, NY. The family of David Remington was living there around the time of Stephen's birth. Could it be that he is their son, and not a son of John? Unfortunately, Boyd Scott Remington did not cite his sources or explain his reasoning.
According to descendant Ann Thompson, Stephen bought land in what is now downtown Pittsburgh, PA. This land, the site of Fort Fayette, was being sold by the federal government, so the deed is signed by President James Madison and Secretary of State James Monroe. Later Stephen & Martha sold this land and the house on it to son Zeri for $1.00.