I have a John TURNBULL, baptized 16 Sep 1799 Roberton, Selkirk. He was the eldest of 14 children, born to James TURNBULL and Mary STAVERT. By 1821, his parents were living in Wilton, ROX, the next door parish to Hawick. So, this John TURNBULL could have married Helen GOODFELLOW. Do you info on their kids, to see if there is a naming pattern connection?
Yarrow is 8.5 miles to the west of Selkirk, which itself is 10.5 miles north of Hawick.
Of course, TURNBULL is a rather common name in the Borders region!