You might want to show us what you have done so far (class definitions, etc…), and provide more detail about the relations you want to implement, so we can provide more specific help.
Are you going to use databases ? how and where are you going to save system data ? are you talking about class relations or database tables relations ?
Sorry to write in this answer box. I don’t know how to edit my question. Here’s a simple readme file I’ve created about my current system design. http://rapidshare.com/files/206049884/Readme.doc.html. Please help!!!