I would like to help, it would be a very interesting exercise. Linda Merle of the Scotch-Irish List may have more recent information on the Millrow First Presbyterian Church, Antrim Parish, N. Ireland.
By entering "Antrim First Presbyterian" in the PRONI catalogue it comes up with 91 entries, but you probably have seen them already.
Would you have a "starting-point list" of names of people who possibly emigrated from that area ?I would say that some who emigrated in the "Boyd" migration of 1718 would have been of that church or nearby, maybe some were tenants of Massereene ?
Would any Adairs in North Ireland be willing to help ? Thankyou.