Just sharing a snippet I used where I needed to change my UI prompts for known versus unknown devices. In the case of known devices, display a custom info box and not giving the tech the option to change the name.
No systems are ever known during prestart because the site has not yet been contacted at this stage in the process. If you need to know the known or unknown state of a system during prestart, you need to make a call to the site using a web service. This is all external to UI++.