I have a signed permission form in my package that gives me consent to take pictures of their child for special crafts ect. However, yes, I was concerned about those okay for taking pictures but not okay with their childs picture being shared with the other parents. So I sent home a consent form for that as well, and in order to have your childs picture in the year book, they needed to sign and return it.
And yes, you are right, it really does suck trying to take pictures with certain children not included.