Hi David,
I am researching same line and here is what I have. I do not have a death record for Christian (nee Bennet) but I believe she died between 1 May 1815 and 1820. I believe she was born 31 May 1775 at Morebattle, Rox and her father was Thomas Bennet. I have been unable to find the marriage date of John and Christian but it was probably about 1799 or 1800. I believe that after her death John married Frances (Fanny) Davidson on 28 Jul 1820 at Yetholm. She was the daughter of James Davidson and Jean Little. Here are the children I have found from both marriages, all born at Yetholm.
Jean, born 12 Oct 1800
Adam, born 25 Dec 1802
Margaret, born 6 Jan 1805
Alison, born 1 Jan 1807
Thomas, born 1 Jan 1809
John, bap. 17 Sep 1811
Andrew, bap. 21 Sep 1813
Peter, bap. 1 May 1815
Children of marriage to Frances Davidson
James, born 21 Sep 1821
William, born 29 Jan 1823 (emigrated to Canada in 1868 with family and half nephew William) He died 6 Sep 1902, York County, Ontario
George, bap. 20 Aug 1825 (emigrated to Canada)
Robert, born 14 Sep 1827
Francis, born 14 Feb 1830
I have traced the Cockburn line back to about 1620 and I have the descendants of William born 29 Jan 1823, above.
Garry