A difficult situation might have been created.
There were talks for a possible engagement of Princess Isabel of Brazil to the then Prince D.Luis of Portugal.
Isabel was the heiress of Emperor D.Pedro II and D.Luis the presumptive heir as D.Pedro V remained childless.
Contacts were maintained between the Emperor of Brazil and Dowager-King D.Fernando II.
D.Pedro V, who had been kept out of the affair, put an end to it when he knew.
Had the marriage had taken place, when D.Pedro V died, D.Luis would have become king of Portugal (as he did) and being married to the brazilian heiress would have been problematic.
Unless he would abdicate on his last surviving brother Infante D.Augusto.
Times were different.
The wedding of D.Jo„o II's only son, Prince D.Afonso, with Infanta Isabel, eldest daughter of the Catholic kings, already had in view a possible unification of the Peninsula, knowing that Isabel's sister, Pr. Juan, was a sicking boy, who died not leaving heirs.
Saddly Pr.Afonso died from a horse fall in circumstances never completely explained, and Isabel returned to her parents' home, childless.
D.Manuel was then offered the hand of D.Maria, second but last daughter of the Catholic kings, which he bluntly refused.
D.Manuel wanted Isabel.This was not just a political wedding but a love one.
D.Manuel knew Pss.Isabel since they were kids and had fallen in love with her.
He had to endure in silence her wedding to his cousin (and nephew) D.Afonso.
When he came to the throne, he made sure he wanted Isabel as his bride and none other.
Not only he loved her, but she was a much better asset in the political chess as the heiress of the Catholic Kings.
D.Miguel da Paz, as firstborn son of king D.Manuel and Q.Isabel was obviously the heir of the portuguese crown.
Had he survived his grand-parents, he would have reigned over Portugal, Castille and Aragon.
Politics were different in the 19th century when the brazilian descendants of Emperor D.Pedro I were excluded from the portuguese succession.
I know that he replaced his mother as heir presumptive to the Spanish crowns, after her death in childbirth. The question is: WOULD it have been possible for inherit them, along with the Portugese crown? I thought that Portugal did not allow their sovereigns to rule other countries. Was that not why the Brazilian emperors and their descendants later on were excluded from the succession? Ditto for the descendants of Queen Maria II through her daughters ...