John Fairbairn (m. Agnes GIBSON)

The revised headstone transcription from an earlier date when it was more legible shows Agnes died aged 37 in "1762?".
The headstone states John and Agnes had a son John (tenant in Westmoriston, married to Jane Romanis) and also implies they had a son William who died aged 9, and a daughter Margaret at age 53. By naming pattern there is likely a James in there somewhere as well given John's parents were shown as James Fairbairn, tenant in Fans and Margaret Henderson.

With a gap between the 1749 marriage for John and Agnes and a John (married to Jane Romanis) born about 1760 there were likely baptisms to be found.
The family previously allocated to John and Agnes: John 1760, Isabel 1761, Agnes 1763 James 1765 and Rachel 1766, although apparently invalldated by Agnes' supposed death date of 1762 all belong to a John, miller at Mellerstain, with Isabel predating Agnes' death, so needed shifting to a different family group.
In addition an Isabel baptized in Nov 1761 is also unlikely to belong to the same family of the John (married to Jane Romanis), who was baptized Dec 1761 to a John tenant in Ligerwood.
These tenants and milllers are prrobably all related but this also does rather indicate a separate famlly group (still looking for a home for them, Dec 2022)

This set of baptisms exist in the Earlston and Legerwood OPRs has now been assigned to John and Agnes (Gibson):
1750 James, father John "tennant in ffans"
1753 Margaret, father John "tennant in Netherthird of Ligerwood"
1757 William father John "tennant in Ligerwood"
1761 John father John "tennant in Ligerwood"
1767 Agnes father John "tennant in Westmorriston"
as it provides a James, along with highly likely baptisms for the Margaret, William and John on the headstone.^8,9
Disambiguation: some trees have the James son of John and Agnes (GIBSON) as the one died Smailholm 1841 after that census, but he was married to a Margaret TAIT, and is more likely to be the son of the John FAIRBAIRN at Girnick, Smailholm in 1797, given the naming pattern of John and Margaret's children.
James and Margaret (TAIT) are buried at Earlston near John and Agnes (GIBSON), so there is highly likely to be a connection, particularly as Margaret's mother was a Mary FAIRBAIRN.

With the Earlston headstones all in a row, it does seem highly likely that there is a connection between these families.
I'm comfortable however that the Girnick Smailholm James belongs to John and Elspeth (ANDERSON), and as they are each contemporaries, any relationship has to be at least two generations further back.

Although "of Legerwood" when James married Isabel Tait, it was also possible, given the miller connections amongst his descendants, that James is the 1765 baptism to John, miller at Mellerstain Mill in 1765, but the ages of the two James don't match up (James m. Isabel Tait born 1765, James son of John & Agnes (Gibson) Fairbairn born 1750.)
The naming pattern of James' children indicates his parents may be a John and Agnes but to date (Dec 2022) both John m. Agnes Gibson and John m. Agnes Brack have been eliminated as candidates.^4,10,11