McKinney & Elizabeth were First cousins.
1850 Lowndes Co MS Census Elizabeth Holderness was listed as 60 years of age,, born in NC  with a property value of $21,000. Harriet age 13 was living with her. She had a total of 53 slaves. McKinney had died earlier that year and is on the mortality Census.
Elizabeth had a considerable estate which she distributed among various nieces, nephews, and cousins.
Buried Friendship Cemetery, Columbus, MS.
Elizabeth IRION and McKinney HOLDERNESS were married on 18 March 1826 in Morgan County, Alabama.74 McKinney HOLDERNESS74 was born in 1792 in Wilkes County, Georgia.74 He died on 9 September 1850 in Columbus, Lowndes County, Mississippi.74,76
[The often seen date of birth for McKinney as 1792 does not seem correct. If Cynthia was his guardian following the death of his father, Lewis McLendon did not carry that forward in 1805. Therefore it would seem that McKinney was 21 at least by 1805 - making him born at least by 1784. Then his father would be too young, but it's also possible his birth year is off. I wonder if perhaps the first McKinnie Holderness was married before Cynthia Powell - maybe she was James' mother but not McKinnie's Perhaps McKinnie married the first wife while still in North Carolina and she never came to Georgia. The two boys seem to be quite far apart in age. Also McKinney never accepted any responsibility for his younger brother, or half-brother - he was in fact gone from Wilkes Co by 1818.]
Elbert Co GA DB R, p.119 2 Mar 1816. Elisha Brewer for $140 to William Irions both of Elbert Co, 20 A adj flat landing on Irions line, up river to mouth of a branch, up the branch to where Irions line crosses branch. Signed: E. Brewer. Wit: Joseph Yates, McKinney Holderness. Rec. 22 Sep 1818.
Had land in Morgan Co AL as early as 1818. Representative to state legislature from Morgan Co AL 1820-1821. One of the founding fathers of Decatur AL.
The 1850 Census enumerator came to this household on 13 December 1850, and he did not count McKinney who had died in September. He is on the Census Schedule for those deceased in 1850. The couple had adopted Harriet Elizabeth Hayden.
Elizabeth IRION and McKinney HOLDERNESS had the following children: