TURNBULLs to FAMILTON?

Still digging away at verifying the link back from my McEWAN descendant Sarah Margery JOHNSTON who married a George Miles/Myles TURNBULL, back up George's TURNBULLs to, supposedly, John TURNBULL and Bessie FAMILTON, the latter being of Earlston.
Admit I'm having a bit of trouble with the chain of evidence.

Can spot John and Bessie (FAMILTON) TURNBULL having children in Melrose, with John saying he was a weaver of Gattonside at his 1718 marriage.
Can spot what looks like their son Thomas marrying Peggy FORSAN and having several children in Melrose, including a John in 1769.

The trail back from George Miles TURNBULL reaches a Thomas TURNBULL married to Helen TAIT, with Thomas stated as born Melrose on both 1851 and 1861 census records, about 1804/5.
I've not seen his 1891 NZ death cert (which implies a birth abt 1801), but at least one tree assigns him to a John and Jane/Jean (CURRIE) TURNBULL, who married/called banns at Cavers (John) and Eckford (Jane) and were having children baptised 1794 (Gattonside) through 1806, but with no Thomas recorded.
The Melrose OPRs also record the burial of a John TURNBULL, feuar of Gattonside, aged 73 in 1827 (so born abt 1754), who would seem unlikely to be the 1769 baptism of John son of Thomas and Peggy (FORSAN) TURNBULL, who didn't marry until 1766.

There is a 1753 baptism in Melrose of a John to John TURNBUL & Janet USHER of Gattonside, witnesses James & John BOSTON, which surname also features as witness to the 1794 baptism of John and Jane (CURRIE) TURNBULL's daughter Janet in 1794, and as cautioner for the 1743 marriage of John TURNBULL to Janet USHER (both of Melrose).

Anyone else interested in these TURNBULLs with any comments? Until more info is available, I'll disconnect the link in my WorldConnect database LornaHenderson.