Looking for advice

I really don’t know where to post this to get the best advice so I figured I’d start here. My 17 yr old daughter works at a fast food restaurant and she told me today that she lied to her manager about what time she could start her shift today because sometimes they make her sit off the clock until it gets busy(she’s a waitress) and then clock in. I have worked very hard to raise her to have a strong work ethic and to let her know she can do anything that she puts her mind to. We live in location: Missouri and I just don’t think this is right. Is there a law against this? Would I be out of line to personally talk to her manager and let them know this is not acceptable and that any type of retaliation against my daughter for said conversation between them and I would not fly. If this is not the place for this post please point me in the right direction. I have looked at the labor board website and can’t find any way to talk to a human being. Thank you for you time.