The Verdict: Need More Info
Your claim turns on finding a record that someone in your family was Brazilian. Start with any Brazilian document in the family and the town or state they came from.
Brazil has no generational limit, so a great-grandparent counts as much as a parent if each generation between can be documented.
Good evidence: a Brazilian birth certificate, an old Brazilian passport or identity card, a consular registration of a birth or marriage, foreign naturalisation papers naming their earlier nationality, or an immigration record. A surname or a family story is not evidence, and consulates will not act on it.
Brazilian registries hold birth records locally, so a town or state is far more useful than a name. Tell us what you know and we will say which record to go after first.