I'm sorry to say I didn't find a listing for Thomas Richey/Ritchey. I have some other Richeys listed if you are interested in those. Don't know if any of them connect to your family.
My suggestion is that you write to the Woodford co clerk and see if there is a will and/or probate for John Richey. That would probably list the names of his children. Were their any Richeys living near the Blackfords as far as you can tell? That may also give you a clue to the parents. Since Woodford co. was created in 1789 from Fayette, you should be looking there too.
i can go through my "Old Kentucky Entries and Deeds" book and see if there are any Blackfords or Richeys listed.
Woodford co. courthouse 103 S. Main St. Versailles, Ky 40383
Be sure to include a SASE so they can respond easily.