I have always installed the portuguese keyboard that comes with bootcamp. However, I have tested the "Brazilian ABNT, Apple - Parallels" as suggested by Maria@Parallels and the mapping of the keys is exactly the same as in the Portuguese (from Portugal) keyboard layout.
The problem is that, as it happened with me, Portuguese people from Portugal don't even try the Brazilian layouts.
Why doesn't Parallels replicate the Brazilian layout with a "Portuguese QWERTY, Apple - Parallels" name?