Now that is interesting.
We have a Flora, daughter of Archibald McConachy of Killean, shoemaker who married Charles McLean a fisherman from Ireland. They both died in the poorhouse. I have posted elsewhere on the forum about them.
The earliest family headstone I have found is this one for their son Charles and his wife RoseAnn Stewart
https://www.findagrave.com/memorial/178 ... es-mclean#There is discussion about this family on Antrim history forum.
I have used family search a bit, and also ancestry at the library, but always there are more questions than answers.
Sounds like this booklet might be helpful.