I'm afraid i have to echo replies already made. Mod staff can usually tell the difference between real multis and people that occasionally log in from a public network. But nothing is guaranteed as you found out last year.
Read this thread: http://forums.cybernations.net/index.php?showtopic=18 for details of who to PM for what. By as Vetinari stated, you will be using a school network, its never going to be safe.
If you go to college and you and someone else regularly share an IP, even if you don't know it, you may get deleted.
If you don't share an IP with your brother you are fine, if you do, you are not.
I refer you to the often overlooked FAQ thread in this room which states:
If you share an IP with anyone else for any reason you face the chance of getting deleted. Honestly its not much more complicated than that.