Around 1694 [his father] James Stewart 5th Earl Galloway (age 23) and [his mother] Catherine Montgomerie Countess Galloway were married. She by marriage Countess Galloway. She the daughter of Alexander Montgomerie 9th Earl Eglinton (age 34) and Margaret Cochrane. He the son of Alexander Stewart 3rd Earl Galloway and Mary Douglas Countess Galloway.

In 1714 Alexander Stewart 6th Earl Galloway (age 20) and Anne Keith were married. She the daughter of William Keith 9th Earl Marischal and Mary Drummond Countess Marischal (age 39). He the son of James Stewart 5th Earl Galloway (age 43) and Catherine Montgomerie Countess Galloway.

In 1729 Alexander Stewart 6th Earl Galloway (age 35) and Catherine Cochrane Countess Galloway (age 20) were married. She the daughter of John Cochrane 4th Earl Dundonald. He the son of James Stewart 5th Earl Galloway (age 58) and Catherine Montgomerie Countess Galloway. They were second cousin once removed.

Before 1751 [his son-in-law] Kenneth Mackenzie Lord Fortrose (age 34) and [his daughter] Mary Stewart were married. She the daughter of Alexander Stewart 6th Earl Galloway (age 56) and Anne Keith.

On 21 Feb 1759 [his son-in-law] John Murray 4th Earl Dunmore (age 29) and [his daughter] Charlotte Stewart Countess Dunmore (age 29) were married. She the daughter of Alexander Stewart 6th Earl Galloway (age 65) and Catherine Cochrane Countess Galloway (age 50). He the son of William Murray 3rd Earl Dunmore.

On 22 Apr 1759 [his son-in-law] Charles Gordon 4th Earl Aboyne (age 33) and [his daughter] Margaret Stewart Countess Aboyne were married. She by marriage Countess Aboyne. She the daughter of Alexander Stewart 6th Earl Galloway (age 65) and Catherine Cochrane Countess Galloway (age 50). He the son of John Gordon 3rd Earl Aboyne and Grace Lockhart Countess Aboyne. They were second cousins.

On 14 Aug 1762 [his son] John Stewart 7th Earl Galloway (age 26) and [his daughter-in-law] Charlotte Mary Greville (age 17) were married. She the daughter of Francis Greville 1st Earl Brooke Warwick Castle 1st Earl Warwick (age 42) and Elizabeth Hamilton Countess Brooke Warwick Castle and Warwick (age 42). He the son of Alexander Stewart 6th Earl Galloway (age 68) and Catherine Cochrane Countess Galloway (age 53).

On 13 Jun 1764 [his son] John Stewart 7th Earl Galloway (age 28) and [his daughter-in-law] Anne Dashwood Countess Galloway (age 21) were married. He the son of Alexander Stewart 6th Earl Galloway (age 70) and Catherine Cochrane Countess Galloway (age 55).

On 25 May 1765 [his son-in-law] Archibald Hamilton 9th Duke Hamilton 6th Duke Brandon (age 24) and [his daughter] Harriet Stewart Duchess Hamilton Duchess Brandon were married. She the daughter of Alexander Stewart 6th Earl Galloway (age 71) and Catherine Cochrane Countess Galloway (age 56). He the son of James Hamilton 5th Duke Hamilton 2nd Duke Brandon and Anne Spencer Duchess Hamilton Duchess Brandon (age 55).

In 1768 [his son-in-law] Granville Leveson-Gower 1st Marquess Stafford (age 46) and [his daughter] Susanna Stewart Marchioness Stafford were married. She by marriage Countess Gower. She the daughter of Alexander Stewart 6th Earl Galloway (age 74) and Catherine Cochrane Countess Galloway (age 59). He the son of John Leveson-Gower 1st Earl Gower and Evelyn Pierrepont Baroness Gower.