Harry and Raona,

Found the following in The Historical Newspaper Collection at Ancestry.com:

Indiana Progress, 9 June 1870, heading "Died":
Keller — On the 13th ult., in Cherryhill township, Mr. George Keller, of dropsy, aged about 75 years.

The 1860 census of Cherry Hill Township, Indiana County
Dwelling House #1466; George Keller Household: George, Catharine, Henry
Dwelling House #1467; John McFarland Household: John, Mary, Albert, Infant, William Davis and another female.
Dwelling House #1469; Thomas Ray Household: Thomas, Hannah, Hannah Davis and others.

In the 1860 census Mary McFarland is listed as age 27; in the 1850 census Mary Keller is listed as age 18. Mary Keller may be Mary McFarland. That could explain why William Davis is in living in the McFarland household.

In the 1860 census living in the household of Thomas Ray is a 9 year old female named Hannah Davis. She is the correct age to be a possible sister of William Davis.
Does the will of George Keller list an heir with the given name of Hannah?

Hope these census conclusions are not too far out in left field.