This isn’t mentioned in Brotherhood, but the reason Roy and Riza came to Resembool scouting out the Elrics is because someone fucked up the ages on Ed and Al’s file.
Literally Roy and Riza are riding in the back of some horse-drawn carriage into Resembool chatting with the driver like “yes we’ve heard rumors of two alchemist brothers here, Ed and Al Elric ages 31 and 30 respectively. Do you know where they live?” And the driver pretty much answers with “lol what? Those kids are like 10.”
Except now Roy and Riza are already THERE so they decide “Fuck it. Let’s pay a visit anyway.”
So everything that went down in the series is thanks to some mysterious fuck up in the Amestrian Intelligence Department and I salute that person.
Bonus: He buries his goddamn face in the document at the end, like staring at it closer might make it less wrong.