Regarding the middle brother's PS "Have you met the Wizard yet?" and Sera's response "you could say so"... I think the brother was asking about Shinichi. Sera's response, "you could say so", makes sense in that she didn't actually meet Shinichi, but she met Conan, so she sort of met Shinichi. Sera apparently knows Conan's real identity already, so this holds together. It seems the event where Shinichi earned the nickname of Wizard was at the beach meeting from the past. Ran specifically mentions "sounds of rippling waves, as if some sort of magic were at work." in Volume 80, File 7 (846), pg 4. I want to put out there for stab-in-the-dark potential that bioluminescent phytoplankton that glow when the water is disturbed would qualify as magical. It implies the middle brother might have also been present at the ocean meeting with Sera, Shinichi, and Ran since he asked about "The Wizard" in the text message. If so, he too could recognize Conan as Shinichi from back then. This would tie in really well with the Shuukichi is the middle brother theory since he is an expert at memorization and could recall Conan's face, which meshes with his immediate treatment of Conan as a skilled detective with no prompting or testing. PS: My guess is that the main body of the message that Sera received was a response to her question of how the brother knows Conan. Sera is of course surprised that anyone would have met Conan since she knows he is Shinichi and thus "shouldn't exist". She would ask this right away. The answer was something mundane like "I met him during a case" and not, "oh I recognize Conan is Shinichi" or the brother would not have followed up with the PS.