I'm not a lawyer but things like this do pique my interest and have read of a few similar situations over on fredmiranda.com.
In general you don't need anyone's permission to take picture in a public place or even of a private place that is viewable from a public space. It's not absolute though as it has been well established that government entities can grant exclusive use and control over public places for events via permits.
The closest analogy I can come up with is let's say that a popular band wants to put on a free concert at the local park. If you were to stand on the sidewalk or street just outside the permitted area of the park, you could take all the pictures you wanted and even sell them without getting anyone's consent. Once you step foot inside the permitted area it's a whole different story though and would depend upon the contract between the band and the organizer as to who would be able to grant you permission and rights to any photos you took (from a commercial standpoint anyway).
In Dane's situation, assuming he's taking these from the sidelines or stands. He should get written permission from the organizers so at the very least it's documented who he is, what he's doing, and what he's doing with the photos. As for getting consent from the parents? I would not open that can of worms as it's really between the parents and the organizers.