One suggestion: a union of the Iberian peninsula in the 15th/16th century under the Transtamara/Foix dynasty
-Frederick III marries Margaret of Anjou
-The marriage of Carlos de Aragon, Principe de Viana and Agnes of Cleves has children:
-Carlos of Aragon, Prince of Viana (29 May 1421 - 23 September 1461) m. Agnes of Cleves (1422 - 1448)
1.Branca of Aragon (January 8, 1441)
-Stillborn (1443)
2.Juan of Aragon (15 August 1445 - 16 March 1453) (Died at age 7)
Stillborn (1447)
3. Eleanor of Aragon (April 9, 1448)
4.Alfonso VI, II and XII, King of Aragon and Navarre and King Jure Uxoris of Castile and Portugal (March 4, 1450) m. Isabella I, Queen of Castile and Portugal (22 April 1451)
-OTL Enrique IV dies on December 8, 1444
-Juan II of Castile marries Leonor of Portugal in 1447
-Leonor of Portugal gives birth to Isabella of Castile (1451) and Alfonso of Castile (1453)
-Juan II of Castile dies in 1454 and Alfonso ascends as Alfonso XII of Castile under the regency of Leonor of Portugal
-Afonso V of Portugal dies in a horse riding accident on March 6, 1455, less than three days after the birth of his son João, who is now King João II of Portugal
-Alfonso XII of Castile marries Joana of Portugal, daugther of Afonso V on February 20, 1469
-Isabella of Castile marries Alfonso II, King of Navarre and Prince of Girona on October 11, 1469,
-Alfonso XII of Castile dies at the age of 16 on January 6, 1470 due to a very high fever, his wife Joana is pregnant
-João II of Portugal marries ??? on January 22, 1470
-Joana of Portugal, Dowager Queen of Castile dies on February 11, 1470 giving birth to a weak and sickly boy, the young baby lives long enough to be baptized and acclaimed as King Alfonso XIII of Castile before dying on March 15 after reigning less than 33 days. Isabella ascends the throne of Castile as Queen Isabella I and her husband as King Jure Uxoris Alfonso XIV
-João II of Portugal and his former regent Fernando, Duke of Viseu (who was unable to have children) died on July 22, 1470 when their barge sank in the Tejo Bay and they drowned at 15 and 36 years of age respectively ( As the order of death of both is unknown, Fernando is posthumously referred to as Fernando II of Portugal), João II's wife is not pregnant and Leonor of Portugal ascends the throne as Queen Leonor I of Portugal
-The sudden death of her son, daughter-in-law and grandson makes Leonor, Queen of Portugal decide to withdraw from public life and settle in a convent, her daughter Isabella becomes her Co-Monarch as Queen Isabella I of Portugal, the Isabella's husband becomes King Jure Uxoris Afonso VI
-The tragic year of 1470 ends on a happy note when Isabella I of Castile and Portugal gives birth to a daughter named Leonor of Aragon
-Isabella I and Alfonso VI, II and XIV have only daughters:
-Children of Isabella I, Queen of Castile and Portugal (April 22, 1451 - July 27, 1516) (Died at 65) and Alfonso VI, II and XIV, King of Aragon and Navarre and King Jure Uxoris of Castile and Portugal (March 04, 1450 - January 14, 1522) (Died at 71)
1.Leonor I and II, Queen of Castile, Aragon, Portugal and Navarre (October 02, 1470)
2.Maria of Aragon (September 08, 1473)
3.Juan, Prince of Asturias, Girona, Portugal and Viana (April 16, 1476 - March 12, 1478) (Died at 01)
4.Juana of Aragon (December 16, 1478)
5.Catalina of Aragon (December 16, 1478)
6.Beatriz of Aragon (October 1480)
Miscarriage (August 1482)
7. Alfonso, Prince of Asturias, Girona, Portugal and Viana (September 18, 1485 - October 18, 1485) (Died at 01 Month)
8.Isabella of Aragon (October 1488)
Miscarriage (February 1490)
--Leonor II ends up marrying Francis Phebo in 1488, who becomes King Jure Uxoris Francisco I