Hello. My name is***** can assist you with your question.
It deftly sounds like there is malware on one or more of these computers. What I would do is run Malwarebytes – you can get that from malwarebytes.org and do a full scan of each computer to make sure that there is no malware on it. If this doesn't resolve the issue, you may want to go as far as doing a complete wipe and factory reset of each system. If you are certain that WebCam access is open publicly, that's pretty serious. And, unexplained behavior like you're having – behavior that seems random, is often due to an abundance of malware, computer.