I hate to be the Debbie Downer of spacetime and causality observation, but if I were in Brazil and had relatives in NYC, there's absolutely nothing that knowing about the 9/11 attacks occurring sooner could have done for me other than given me additional hours to wait anxiously for news from my loved ones.
Phone lines were jammed into the city (including cellular, because the circuits were saturated), and nobody was flying in or out of NYC. So unless someone in Brazil is secretly Clark Kent, there's 100% nothing they could've done to help or hinder the fate of the 9/11 victims in the hours after the attacks.