You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
alternatehistory.com
"A further marriage between the Portuguese and English royal families occurred in 1662 when Charles II of England married Catherine of Braganza, daughter of King John IV of Portugal."
Since I didn't bother researching the royal line of Portugal, what if, all male sons of King John died (with no heirs), and Charles and Catherine had a male child, heir to both thrones?
Basically, what would happen if the King of England was the King of Portugal too?