I am a researcher of Preble County Holes and saw your posting on McGriff.I believe that from the 1850 Census that Charles Hart provided, your Mary is the daughter of William and Elizabeth Hole McGriff.
I didn't have dates on Mary (only that she had to have been born after 1800 and alive after 1880), but Elizabeth, her mother, was born in 1792 in Virginia."History of Preble County" says she died in 1875.
I have 14 children born to William and Elizabeth and info on Elizabeth's parents (Zachariah and Hannah Delay Hole) and grandparents (Zachariah and Phebe Clark Hole) and extended family. Let me know if you are interested. Very interesting family that settled first what is now known as Miamisbutg. Mostly from bios but also have the Common Pleas Court of Preble County info - one court case in 1837 lists a lot of the family.
Also, please let me know if this Mary is indeed the same that married Mr. Dupy so I can add him to my info.