Dutch Reform Church records of New Hackensack, Dutchess County, NY, show that David Algee and Mary Pinckney are parents of son John baptized January 1792. Marriage records for this church for the few years before 1792 are missing. There are no mentions of either Mary Pinckney or David Algee in the records of this church, which go back to 1765, There are several Pinckney families in Dutchess county at this time. I think she belongs to one of them, but haven't been able to link her up with any. (I don't know where David came from either; I'm hoping that if I find Mary's origin, that might give me some idea about where to look further for him.) In general, I'm thinking that the Pinckney families of Dutchess county probably came up from Eastchester, in Westchester County.