I do not think my Flemings lived in Chester County, but I did gather up some info along my journey.
Here is one other person's opinion: "Robert Fleming of Londonderry twp., Chester, PA, d. 1742, leaving wife and son David.In his will he mentioned grandsons John and Robert Fleming, this latter Robert died in Oxford Twp. in 1772 leaving his father, David and brothers John, James, and David.David Fleming of Oxford died April 5, 1784, aged 73, devised to son John L50 and to son David the land.this David was living in Green Co., KY or Tenn., in 1795."
There is a David Fleming buried in the Upper Octarora Presbyterian church Cemetery in Londonderry Twp., Chester, PA, who died 5 Apr 1784, aged 73.
This is a difficult line, and I do have a lot on uncertainties about it myself.