Okay Barney Fife. If you don't want parents, whom you know, to show up at school in a state of worry, don't call them and tell them there's something wrong with their kid and to come down and then expect them to not act like a worried mother.
Mama Bear/Cub. Don't get in the way Barney or you'll lose your ass - in this case via lawsuit.
Apparently the idea that we must “break through our kind of private idea that kids belong to their parents, or kids belong to their families, and recognize that kids belong to whole communities” is gaining traction on FR.
Don’t you realize that the students were in danger because a mother didn’t sign a magical piece of paper?
</sarc>
You identify if they actually are the person who is permitted to have access to the child. That paperwork, which is submitted upon enrollment is signed, stating who has the permission for access to the child. A phone call can be received by anyone in the house - and so, whoever “shows up” is not necessarily the person who has permission to access the child.