Make the United Kingdom of Portugal, Brazil and the Algarves, (Comprised of Portugal, Brazil, Angola and Mozambique) formed after the Napoleonic wars and which lasted 2 decades irl exist in one way or an other until either the 20th or 21st century.
I think the only chance of that happening is with Brazil being divided into many countries inside the Union and then being bombarded with heavy propaganda to evolve an unique identity to each country, yet tied to a common Portuguese identity.
If you maintain some 4 or 5 different countries in Portuguese America with distinctive identites they might never unite and realize they easily outbeat the metropolis.
Another thing is there would have to be lots of negotiations between Portuguese and Brazilian elites. Portugal already knew in 1822 that Brazil would overshadow it's colonizers and dominate the Union, that's why they wanted to make it a colony again. Maybe they could agree on some kind of under representation for Brazil that would be progressively abandoned until idk the 20th century, after that Portugal would have no choice than being the junior part in the union.
Best bet is a divided Brazil.
Other possibilities mainly involve a earlier POD that would make things irrecognisable
It is often the case that people on this forum have miscellaneous or frivolous questions that could be easily answered by the many experts on this forum but are difficult to find the answer to on Google Scholar/Books or Wikipedia because they don't often deal in alternatives. There are other...