I've been having a very hard time trying to find any of your policies for minor attendees, so I have two questions:
1) Kids won't need state-issued ID to register at the door, will they?
2) I am planning on chaperoning three teenagers (ages 15-16) on a trip to the con this year. We are coming from Oregon. I am not a parent, but have permission slips from their parents. I have done this before at Sakuracon in Seattle and Kumoricon in Portland. Sakuracon in particular has a form they require the parents of kids to sign in order for them to be able to attend the convention which designates an "attending adult." (https://secure.sakuracon.org/registration/parentalauth.php)
Is there such a form for Fanimecon? I can't seem to find one, and the "Policies and Rules" page only links to the weapons policy. (http://www.fanime.com/about/policies) I would hate to drive all the way down there only to find out we haven't jumped through the proper hoops and can't attend the convention.
Make sure the little ones have their receipts, or some sort of parents consent. Inform the staff that you're the acting guardian. Other than that, I am not exactly sure how you should go about doing this.
Over the years bringing minors has been like pulling teeth for me, luckily most of my friends are now in the 20's range or a year younger/older give or take.
My opinion, handle things you can, when you can, get consents and receipts now, not from some phone call at 4 in the afternoon in San Jose. And make sure those kids have Passports, or some sort of government ID.
The government ID is to pick up badges that have been pre-paid, if you're buying their badges at the door any sort of ID should work, I believe?
I would consult a GM or Admin first. But as far as I am aware of, a government ID like a passport or the picture I.D. works. If that isn't accessible there are others ways to get in, it just takes a little longer, also please please please bring your receipt!