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I was thinking since the Habsburgs' Mary of Burgundy, Franz , the OTL dead son of Mary of Burgundy can actually be used for their claims in Portugal, since Eleanor, the Holy Roman Empress is a Portuguese infanta, could Franz be declared as the heir of John II and marry Isabel, he would be 17 when would be king and Isabel of Aragon would be 28 but that would not be an impediment.
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