If you're planning to bring Kids?

[xenzii]

So I'm going to pre-register for next year (whenever the site comes up) and I'm planning on bringing my younger cousins with me.
Do I have to pay and pre-register them too? Or do they get in for free?
One is 12 and the other is 9.

Also, do they need some sort of ID?

[echoshadow]

to quote Fanime's faq's:

Q: Are kids 10 and under free?
A:Yes, kids 10 and under are free. However, you would need to register them at-con to get their child badge.

Q: I am under 18 and do not have a driver's license or passport, what do I do?
A: All FanimeCon members must have valid government issued ID. If an attendee is under 18 and does not have a government-issued photo ID, they can still pick up their badge if their legal parent or guardian accompanies them and the legal parent or guardian has a valid government-issued photo ID that is consistent with information on the attendee's registration. The parent or legal guardian is not required to purchase a badge and does not need to accompany the attendee at all times, but they will still be responsible for the attendee's action.

So by this you still have to register them and pay for you and your 12 year old cousin, the 9 year old gets a free pass.
I would check again when the new registration for 2013 opens up, some policies may or may not change.