On 26 Apr 1411 [his father] John Jacob Marquis of Montferrat (age 16) and [his mother] Joan of Savoy were married. She the daughter of Amadeus "Red Count" Savoy VII Count Savoy and Bonne Valois Countess Armagnac and Savoy (age 46).

On 19 Jan 1465 William VIII Marquis of Montferrat (age 44) and Marie Foix Marquis Montferrat (age 13) were married. She by marriage Marchioness Montferrat. The difference in their ages was 31 years. She the daughter of Gaston IV Count Foix (age 42) and Eleanor Trastámara Queen Consort Navarre (age 38). They were third cousin once removed.

On 14 May 1468 [his future brother-in-law] Jean III Brosse and Louise of Laval (age 27) were married. She a great x 5 granddaughter of King Henry III of England.

On 06 Jan 1474 William VIII Marquis of Montferrat (age 53) and Bernarde de Brosse Marquis Monferrat were married. She by marriage Marchioness Montferrat.

On 27 Jun 1474 Francis Montfort II Duke Brittany (age 41) and [his former sister-in-law] Marguerite Foix Duchess Brittany (age 25) were married. She by marriage Duchess Brittany 1364 War of Montfort. She the daughter of Gaston IV Count Foix and Eleanor Trastámara Queen Consort Navarre (age 48). They were second cousin once removed. He a great x 4 grandson of King Henry III of England.

On 19 Aug 1479 Jean V Count Armagnac and [his former sister-in-law] Jeanne Foix were married. The difference in their ages was 34 years. She the daughter of Gaston IV Count Foix and Eleanor Trastámara Queen Consort Navarre. He the son of John IV Count Armagnac and Isabella Évreux Countess Armagnac. They were first cousin once removed.

After 1483 Philip "Landless" Savoy II Duke Savoy (age 44) and [his sister-in-law] Claudine Brosse (age 33) were married. He the son of Louis Savoy I Count Savoy and Anne Cyprus Countess Savoy. He a great x 5 grandson of King Edward "Longshanks" I of England.