The world of the United kingdom of Portugal and Brazil survives and British Argentina

In this world, Brazil continues to be the capital of the Portuguese empire and it is capable of maintaining all its Portuguese colonies and Portugal itself.

And Argentina is conquered by the British during the Napoleonic wars.

What would that mean for South America and the world?

How would British Argentina affect immigration to the domains? (canada, australia, new zealand, south africa and etc)

And because Argentina never existed, would that be beneficial for the Brazil-Portugal union?
since its biggest rival never existed and the lands that would be Argentina are controlled by the traditional ally of Brazil-Portugal, the British