PS: Just to tell you, using a real airline name isn't too safe either. Sure, your name is "Cathay Express" and your brother's airline is "Fly Cathay", but CPA has the right to sue you for copyright infringement. Hell, they tried suing CPA Virtual even though they had links saying "We're not CPA - click here to visit Cathay's webiste", acknowledged all their sources, and even said they aren't endorsed and sponsored by Cathay. Fortunately, CPA did mind too much since they had such a following, but remember that you aren't safe either.
Phew.
Cathay is known to be quite insane with their copyright protection. I, like most people on this board probebly do collect Diecast airliners, and the only ones that have the proper manufacturing rights produce them exclusivly for CX, so there are pirated models floating around that CX goes around trying to find and take legal action against, even though I see them sueing AM or the 2 involved here as a very bad PR move if they do. Otherwise, they would need to start sueing people who play Aerobiz on the Super Nintendo and name their airline "Cathay Pacific" (Free game, player is not profiting off the name). AA is sorta the same too until recently when it came to (free) Flightsim repaints, if you wanted to do one, you had to obtain the licnese from AA or state that you're not affliated with AA. I remember someoen made a "American Sucks" DC-9 over that for Flight Sim 98.
Anyways, after reading all 7 pages of this I'm gonna have to say, it would be highly difficult to prove that Cathay Express's brother does play this game and the best proof (and maybe the only way) is someone visiting him and watching him play. Though I'm highly amazed that a 6 year old would be very interested in playing AM let alone know how to play it (though like dktc said, he could be just really smart). If I was his age, I probebly would be bored to death since it wouldn't interest me at such a age when I'm still learning basic math and how to read, but that is my opinion. The fact you guys had a similar name and a id number very close to each other sets off alarm bells to most anyone who is paying attention. But I would try to be polite to the admin, they do have a very hard job to do making sure that there is no one cheating. I guess the best thing to do is to wait until your banning period is over.