On 18 Jul 1807 [his father] William Cavendish (age 24) and [his mother] Louisa Ocallaghan were married. He the son of George Augustus Henry Cavendish 1st Earl Burlington (age 53) and Elizabeth Compton Countess Burlington (age 47).

On 07 Mar 1822 George James Welbore Agar 1st Baron Dover (age 25) and [his future sister-in-law] Georgiana Howard Lady Dover (age 18) were married. She the daughter of George Howard 6th Earl Carlisle (age 48) and Georgiana Cavendish Countess Carlisle (age 38). They were third cousins.

On 14 May 1823 William Lascelles (age 24) and [his future sister-in-law] Caroline Georgiana Howard (age 19) were married. She the daughter of George Howard 6th Earl Carlisle (age 49) and Georgiana Cavendish Countess Carlisle (age 39). He the son of Henry Lascelles 2nd Earl Harewood (age 55) and Henrietta Sebright Countess Harewood.

In 1829 William Cavendish 7th Duke Devonshire (age 20) and Blanche Georgiana Howard Duchess Devonshire (age 16) were married. She the daughter of George Howard 6th Earl Carlisle (age 55) and Georgiana Cavendish Countess Carlisle (age 45). They were second cousins.

On 12 Aug 1840 Francis Richard Grey (age 27) and [his former sister-in-law] Elizabeth Dorothy Anne Howard (age 23) were married. She the daughter of George Howard 6th Earl Carlisle (age 66) and Georgiana Cavendish Countess Carlisle (age 57). He the son of Charles Grey 2nd Earl Grey (age 76) and Mary Elizabeth Ponsonby Countess Grey (age 64). They were third cousins.

In 1842 [his former brother-in-law] Admiral Edward Howard 1st Baron Lanerton (age 32) and Diana Ponsonby Baroness Lanerton were married. He the son of George Howard 6th Earl Carlisle (age 68) and Georgiana Cavendish Countess Carlisle (age 58). They were third cousins.

On 08 Aug 1842 [his former brother-in-law] Charles Wentworth George Howard (age 28) and Priscilla Harriet Parke were married. He the son of George Howard 6th Earl Carlisle (age 68) and Georgiana Cavendish Countess Carlisle (age 59).

In 1845 [his former brother-in-law] Henry George Howard (age 26) and Mary Wellesley MacTavish (age 19) were married. He the son of George Howard 6th Earl Carlisle (age 71) and Georgiana Cavendish Countess Carlisle (age 61).

In 1852 Henry Labouchere 1st Baron Taunton (age 53) and [his former sister-in-law] Mary Matilda Georgiana Howard Baroness Taunton (age 28) were married. The difference in their ages was 24 years. She the daughter of George Howard 6th Earl Carlisle and Georgiana Cavendish Countess Carlisle (age 68).

On 07 Jun 1864 [his son] Frederick Charles Cavendish (age 27) and [his daughter-in-law] Lucy Caroline Lyttelton (age 22) were married. No issue. He the son of William Cavendish 7th Duke Devonshire (age 56) and Blanche Georgiana Howard Duchess Devonshire. They were third cousins.

On 03 Aug 1865 [his son] Edward Cavendish (age 27) and [his daughter-in-law] Emma Elizabeth Lascelles were married. He the son of William Cavendish 7th Duke Devonshire (age 57) and Blanche Georgiana Howard Duchess Devonshire. They were first cousins.

On 26 Sep 1865 [his son-in-law] Francis Leveson-Gower aka Egerton (age 41) and [his daughter] Louisa Caroline Cavendish (age 30) were married. She the daughter of William Cavendish 7th Duke Devonshire (age 57) and Blanche Georgiana Howard Duchess Devonshire. He the son of Francis Leveson Gower aka Egerton 1st Earl Ellesmere and Harriet Greville Countess Ellesmere (age 62). They were second cousin once removed.