Alexander Mitchell?s marriage to Agnes Christy was registered in Ballymoney Apr ? Jun 1893, volume 1, page 179. If you order a copy of that marriage certificate you should get their fathers names and other information to aid taking the line back.
This looks to be them in the 1901 census, farming at Livery Lower:
http://www.census.nationalarchives.ie/pages/1901/Antrim/Dervock/Livery_Lower/945571/
and in 1911:
http://www.census.nationalarchives.ie/pages/1911/Antrim/Dervock/Livery__Lower/129310/
The revaluation records show that Alexander acquired the farm in 1894. It was plots nos 8 & 9, and consisted of a farmhouse, outbuildings and a combined total of 6 acres of land (subsistence farming). That today is between the Livery Rd and the Feigh Rd.
This looks to be Thomas O?Brien and Sarah Ann Daley in 1901 in Ballyratahan Upper:
http://www.census.nationalarchives.ie/pages/1901/Antrim/Dervock/Ballyratahan_Upper/945446/
The Griffiths revaluation records indicate he moved there in 1901 and left in 1911
and in 1911 in Dervock town:
http://www.census.nationalarchives.ie/pages/1911/Antrim/Dervock/Dervock_Town/129379/
There were other O?Briens living nearby according to the revaluation records:
http://applications.proni.gov.uk/DCAL_PRONI_Val12b/ImageResult.aspx
The marriage of Thomas O?Bryan & Sarah Ann Daly was registered in Ballymoney 1875, Volume 16, page 219.
