Ruth,
Here’s a marriage between James Adair & Mary Stewart in 1850 in the right area.
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1850/09383/5398472.pdf
James lived in Enoch (Enagh) and his father was Joseph Adair. Tradition was to marry in the bride’s church so that was Ballyroney Presbyterian. You might find the Stewart family’s baptisms etc in their records. That church’s records start in 1819.
1st Dromara Presbyterian has baptism records from 1762 onwards and marriages from 1799 with a few gaps. Copies of both churches records are in PRONI (the public record office) in Belfast. If you are unable to go yourself, you could employ a researcher. Researchers in the PRONI area: http://sgni.net
Possible death for Mary Adair registered in Lisburn 3.1.1865 aged 48. D/1865/139/1018/1/118 You can view the original certificate on-line on the GRONI website, using the “search registrations” option. You will need to open an account and buy some credits. It costs £2.50 (sterling) to a view a certificate:
https://geni.nidirect.gov.uk
Griffiths Valuation (1863) lists 1 Adair property in Enagh. That was plot 32 which was an 11 acre farm, held by John Adair. Perhaps a relative to James? That property today is on the modern Shot Lane, not too far from Garvaghy Presbyterian church. Looking at it on Google Earth, it’s still a farm, today.
http://www.askaboutireland.ie/griffith-valuation/index.xml?action=nameS…
There was still Adairs farming in Enagh in 1901:
http://www.census.nationalarchives.ie/pages/1901/Down/Gaevaghy/Enagh/1205366/
And 1911. They had no children:
http://www.census.nationalarchives.ie/pages/1911/Down/Garvaghy/Enagh/214053/
You’ll find details of some of James & Mary’s childrens’ baptisms on this link:
http://freepages.rootsweb.com/~rosdavies/genealogy/SURNAMES/A/Adair.htm