Legal Question in Civil Rights Law in Missouri

You're asking a question with a distinction that you may not realize. Legal usually refers to whether an act violates some criminal statute or ordinance. Lawful usually means whether that act(or omission) can subject a person to civil liability. Unless there is a pornographic or commercial use of the picture, it is probably not illegal to put the picture on an individual facebook page. But, as the parent, you can sell damages and an injunction, if it isn't removed upon your request. As a commercial enterprise, facebook itself can be liable for not getting the unauthorized photo off, as well as the page owner.

Good luck