Message from Professor Linde Lunney on the Abernethy Family Genealogy Forum :
"You are in luck with Mill Row; it has very early records, some of which even have been indexed. Baptisms 1677-1733, 1753-1785, 1791-2, 1820-1960. marriages 1675-1736 1820-1839, 1845-1919 deaths 1820-35 etc Microfim in PRONI 1P/3 C.r. 3/2 I'm sure the LDS centres can get it for you. It's unusual for a Presbyterian church to have such old records. Linde Lunney "
These records may be in the Presbyterian Historical Society, Belfast.