What type of record do you have showing that Nancy Ann Allen married William Cannon/Kennon? Others have also posted that Nancy Ann's sister hannah married Reuben Cannon/Kennon. I am a descendant of Reuben Kennon.
I believe that his father is William Kennon, who died intestate about 1854 in Caswell Co., NC. If I am correct, then my information aligns with yours. Your William and my Reuben would be brothers.
Reuben Kennon died intestate in 1858 in Caswell Co. Estate records show that his wife is named Hannah. Hannah is listed in the 1860 ccensus for Caswell Co. and Person Co. is given as her place of birth.
I would like to exchange information with you.