You'd have to make sure every MC has his/her own voice - if you find that two of them have similar voices, you can always morph them into one character. A character has a role to fulfill, so if the role is minor, the character can be minor, if the role is major, the character can be a main character. Good luck with the story!
Mammamaia: thanks for the tips, I'll try to find it. Edit: I just saw they have it at the library, I'll check it out tomorrow!
I personally couldn't handle that number of MC's, but have read books with about the same. I agree with the others; it's more about how you do it, than if it can be done.
Keep in mind that a main character is not necessarily a POV character, or vice versa. The main character or characters are those the story revolves around. A POV character is an identified or virtual character who "reports" the story to the reader. The POV character is the voice behind the narrative. In Sir Arthur Conan Doyle's famous detective series, Sherlock Holmes is the main character. The POV character, on the other hand, is Doctor John Watson. There are narrative advantage to the POV character being distinct from the main character.
Like the above posts I agree that if you think you can make it work, then write it! George Martin did an awesome job of this, so maybe check out his books?
Cogito: You're right, I didn't clarify that in my post but I actually thought of letting all 6 (now) of them having their own POV, because that is kind of what the story relies on.
