I think that I remember reading that Disney was getting more strict about what defines a youth "group". They're asking for legitimate proof that the kids in your group actually exists as a group outside of Disney World. That might be why you don't see any YES groups forming anymore.
There are opportunities for individual enrollment but the dates are more limited. Check the YES website to see if they have anything for your trip. http://www.disneyyouth.com/individual-enrollment/
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