The four sons of George Clazy b.c.1730, m.Agnes Middlemist b.c.1730 are
1. William b.1753, Coldstream.
2. John b.1755, Coldstream.
3. James b.1760, Coldstream.
4. George b. 1765, Mordington.
1. William m.Isabella Thomson c.1784 - issue found - 7 (5boys, 2girls) eldest son
1.1 George b.1786, Hutton; probably m.Margaret Brack 1812, Bunkle & Preston.
2. John m.Margaret Palen 1777, Hutton - all issue known to have emigrated to Australia (see previous posts by others)
3. James m.Helen Ker 1786, Hutton/Chirnside - issue found - 9 (5boys, 4 girls) - eldest son
3.1 George b.1787, Hutton; m. Jean Lockie c.1812 - issue found - 8 (2boys, 6girls) - eldest son
3.1.1 James b.1816, Edrom (named after paternal grandfather which follows the convention of that time, as does the names of the rest of the children)
4. George m.Agnes Alexander 1793 Foulden - issue found - 6 (3boys, 3girls) eldest son
4.1 George b.1793, Foulden; m.Rabina Bell 1820 Kelso - issue found - 5 (1boy, 4girls) -only son
4.1.1 George b.1824, Eccles (named after paternal grandfather etc. etc.)
I have found no other Georges registered in that period in Berwickshire, Roxburghshire, or indeed anywhere else in Scotland: nor are there any 'orphans' which would suggest another line. [I have time lined all recorded Clazy (and associated spellings) births,marriages and deaths recorded in Scotland.]
This would therefore point to George, son of William and Isabella Thomson, being married to Margaret Brack.
Although their children do not follow the naming convention of the time entirely, the first female child, Agnes, is named after the maternal grandmother, the second female child, Isabella, is named after the paternal grandmother, and the third female child, Margaret, is named after the mother - all as was the convention of the time. The first male child is George, named after the maternal grandfather (and/or father), the second is un-named, and the third is William - not as the convention, although the William is significant. Perhaps there was an earlier William who did not survive, between Agnes and George?
I think the female line names, the birth locations of George and Margaret, and the lack of other possibilities clinches it anyway, notwithstanding that there were many unrecorded births etc..
I have lots of records of the Clazy family and if there is anything particular you would like a copy of please drop me an e-mail.