I appreciate the detailed information. Joseph Koon was my great-great-great grandfather.
Joseph's son Thomas had two wives. The 1850 census I have from a second cousin notes the first wife Katharine and two sisters you mentioned an infant, Thomas's brother John and a hired hand. Emma Koon was a daughter of the second marriage and lived from 1859 to 1863. The 1850 census refered to a one year old femaile infant who may be Matilda. I do not know of any one else named Matilda Koon.
I am descended from the second marriage.Thomas married Caroline Moffett on May 6, 1852, [his first wife Katharine or Catherine Corgell(korzell maybe?)died January 15,1852] and on December 2, 1854, Francis Marion Koon was born.By the 1880 census, Thomas is reported as being either widowed or divorced per the census and living with Francis and Francis's family but no mention of Caroline.However, Caroline died in 1903 and Thomas died in 1897 both in Johnson Township in La Grange County Indiana so they either separated or divorced.Francis had several children including my grand father John who is deceased.