King Henry I of Portugal must marry

The Infante Henry was the son of King Manuel I of Portugal.
Early in his life, Henry took Holy Orders to promote Portuguese interests within the Catholic Church. He rose through the Church hierarchy. He became an archbishop and eventually a cardinal.
Henry served as regent for his grandnephew, King Sebastian. He succeeded Sebastian as King of Portugal.
King Henry attempted to renounce his ecclesiastical office and sought to get married for the continuation of the Avis dynasty.
Pope Gregory XIII did not release Henry from his vows.

Suppose the Pope releases King Henry from his vows. Who does King Henry I marry?
 
Well, for starters Pope Gregory XIII would have to not have the reasoning of King Philip II lusting for the throne ... either by not having them being close personal friends (whom pushed heavily for getting his old friend on the papal seat) or by Philip failing to get Gregory XIII on the throne, say France and England argeeing that an Hapburg friendly pope is a very bad idea, throwing their lot behind someone else deadlocking his election, the chair ending at someone more willing to argee with him.
 
He could marry in contravention of Church law and then take steps, as King, to ensure his children by this uncanonical match succeeded.
 
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