Ok lets establish a few things I am not the author of the TL and I had suggested that it would of been great that Portugal gain some land in the Castile Civil War. Therefore they have, but had to horse trade with other powerful member of the Castilian nobles who also vied for the throne and Portuguese accepted someone else becomes king of Castile and marries king Alfonso's daughter. For the Portuguese to of succeeded in the war they would of needed to of allied with some Castilian nobles who get to replace Isabel. My own personal opinion is I do not like personal unions, the Portuguese have enough work trying to incorporate Galicia and Leao never mind Castile, that just a Spain with capital in Lisbon and dominated by Castilian nobles. Few of those TL around. I like the fact we got part of Portuguese historic claims and left Castile alone.
I understand that there were two rightful heirs to the throne Isabel and Juana. The best alternative would be for Juana to be recognized the heir but that she gets very sick and dies shortly after the treaty and a new Castilian king is chosen who marries Alfonso daughter. Have Portugal get Heulva or something as compensation.
Yes Isabel and daughter are shipped out to sicily and under the new King of Aragon.
alright the timing was murky to me but makes sense that with Ferdinand out of picture certain wedding and unions be altered.
What I was saying is that king Afonso claim to Castilian throne was through his wife and not his daughter and since he never had any children with his 2nd wife the only person who could be placed on throne be his daughter from previous marriage whose mother was Portuguese. So without an heir from his 2nd wife to guarantee the union the Portuguese were always at loss. Alternatively we could have a temporary union that could be broken by birth of boy from 2nd wife in 1478. That child would become Castile heir while John becomes Portugal king. But do not see John being crowned both king of Castile and Portugal.
Again. Alfonso V of Portugal will be King of Castile jure uxoris but we will not have any permanent unification between Castile and Portugal as the two kingdoms will have different line of succession:
Castile: line of succession to Juana I, Queen of Castile and Queen Consort of Portugal:
a) eventual sons of Queen Juana (by King Alfonso or another successive husband) and heirs in birth order
b) eventual daughters of Queen Juana (by King Alfonso or another successive husband) and heirs in birth order
c) Isabella of Castile, Queen Dowager and Regent of Sicily, Dowager Princess of Girona, Infanta of Castile
d) any eventual sons of Infanta Isabella from a future wedding and heirs in birth order
e) Isabella of Aragon, Queen of Sicily, Infanta of Aragon, eldest daughter of Infanta Isabella of Castile, and her heirs
f) any eventual daughter of Infanta Isabella from a future wedding and heirs in birth order
g) John II, King of Aragon and Navarre
h) Eleanor, Princess of Viana and Infanta of Aragon, King John’s eldest daughter and heirs
i) Infanta Juana of Aragon, Princess of Girona, King John’s younger daughter and heirs
j) Enrique, Prince of Girona and Duke of Segrobe (husband of Infanta Juana of Aragon)
Portugal: line of succession to Alfonso V, King of Portugal
a) João, Prince of Portugal
b) Infante Alfonso of Portugal, eldest son of Prince João and heirs
c) any eventual younger son of Prince João and heirs in birth order
d) any eventual daughter of Prince João and heirs in birth order
e) any eventual other son of King Alfonso (by Queen Juana) and heirs in birth order
[Juana, Infanta of Portugal, eldest daughter of King Alfonso, actually in convent]
f) any eventual other daughter of King Alfonso (by Queen Juana) and heirs in birth order
g) Infante Diogo, Duke of Viseu and Duke of Beja and heirs
h) Infante Manuel of Viseu and heirs
i) Infanta Leonora of Viseu, Princess of Portugal (wife of João, Prince of Portugal)
j) Infanta Isabella of Viseu, Duchess of Guimarães and heirs
So the only case in which Castile and Portugal will stay united after the death of Alfonso V is if the line of João die and a child of Alfonso and Juana inherit both crowns. As Juana I is only 17 years old at the end of the war is pretty likely who they will have soon children (in OTL at this point their wedding was annulled, she was recognized as an illegitimate daughter of her mother and practically recluses in convents for the rest of her life).