How do you know that Sarah was born to Joseph and Elizabeth Simon?

Joseph and Elizabeth Simon had moved to Liberty Township, Crawford County, IN prior to 1860.

Morgan is a common name in both Crawford County and Daviess County, IN.

I found a Henry Morgan living in Crawford County, IN married to a Sarah E. ___________ born in IN.

I found a James M. Morgan living in Daviess County, IN married to a Sarah A. __________ (26) born in IN.

Also found a Sarah Morgan (20) in Hamilton County, but she was living with another family.