Thanks for your message. Raona very kindly transcribed the text of the G Keller will and you can see that Mary MacFarland is indeed G Keller's daughter. The only Hannah in his will is his daughter who was married to Issac Mentch, and she was much older than Hannah Davis.
The existence of Hannah Davis upsets my theory that William Davis was the illegitimate son of one of G Keller's daughters, and would later change his name to William Keller.
Raona just posted some more information about W B Keller that has some new clues.
Regards,
Harry Raab