I don't know her family, but I'm interested. My ancestor Gavin (Guian) McKee (1751-1827) came from the vicinity of McKeesport and settled in Fleming Co., KY, in 1789. By wife Abigail he had children born between 1777 and 1791. His son Robert's widow Elizabeth married a second time in Adams Co., OH, in the 1810s.
Have you checked for other McKees in Adams County in that time period? What were the names of Susannah's children? What is the source of the information that she was born in McKeesport? If so, there is a strong likelihood that she was related to Gavin's family----even a daughter. Abigail was born about 1754, so she would have been about 40 when Susannah was born.
James McKee, younger brother of John McKee, who founded McKeesport, left the area, but I don't know where he moved to. He could be a possibility.