Oh, sure. YAGMCB and Snoopy are both very easy to add choruses to. During The Baseball Game, for instance, the director at one of our middle schools split the cast of sixty or seventy into two teams and staged a baseball game between them. Beethoven Day featured the eighth grade cast members, who were all decked out in Beethoven sweatshirts and selling Beethoven cookies. The chorus easily becomes school children or neighborhood kids, and it all tends to work really well.
(P.S.: Snoopy is, in my opinion, a little more chorus-friendly than You're a Good Man, Charlie Brown. If you've got any sort of sway at all, why not suggest it?)
Best of luck!
"'But do you really mean, sir,' said Peter, 'that there could be other worlds --all over the place, just round the corner-- like that?'
'Nothing is more probable,' said the Professor..."
-The Lion, the Witch, and the Wardrobe