I am having an incredibly busy day but did look at my family history today.
Hezekiah D. Davenport died in 1850 and lists his wife as Frances J. Davenport.
You state that Nellie died in 1848 so perhaps Frances J. is his 2nd wife as she was still alive in 1870 on MI census living with Stillman and his new wife. She was 65 then.
This may be the answer to this confusion. Hezekiah's youngest child, anson was born in 1840 so all of the children listed in his will could have been born to Nellie before her death.
Their children were: Benjamin B, Thomas D, Ruth, Nelson, Amos and Charity,Sarah Ann and Anson in chronological order.
I will get back to you on this. The deeds I found were on USGenweb site for Tompkins Co. Apparently when Hezekiah died he left some of his land to his sons and they sold their shares to Frances J. just before they all left for MI.
Do you know when Frances died and where she is buried, MI I would guess.
Wendy Sheldon Black