Reading up on the Portuguese Revolutionary Wars I became interested in a possible ATL.
Pedro's liberals dominated the sea and were backed by Britain and although he had abdicated the Brazilian throne, had connections during the war. Let's say Miguel's absolutists defeat the liberals on land in Portugal. Pedro dies. Maria is forced to flee to friendly Brazil, establishing a shadow government that is doomed bar one or two minor invasions, never to return to Portugal proper.
Taking naval power, British support and Brazil's ties to the slave trade in Angola into account, could Portugals overseas colonies end up de facto under Brazil's control, in a caretaker capacity for Maria and her heirs, possibly becoming de jure as part of a deal to back an invasion or simply through dynastic crossover, ie the Brazilian Emperor/Emperess becomes the Pedristo claimant.