Audrey Franklin at this forum says that Anna NORTHCRAFT was the second wife of Thomas LEGG b. 13 Jun 1753, son of John LEGG. If she's correct, that leaves the way open for John's wife to be a daughter of Thomas CONN.
Thomas LEGG was in Washington Co. PA around 1781 and died there in 1801. His younger brother Charles was also in Washington Co. PA. It's possible that their parents were there in 1763, thus the payment in PA money.