Enforce a participant to enter a name upon joining meeting?

We hold many meetings with small subsets of a fairly large group of doctors. We send the meeting invitation to all and then whoever is interested and available will join. Unfortunately, usually the last person to use the device is their kid so when they click on the link and join, the name that's displayed is usually something silly. None of them know how to change the name and it's awkward and time consuming for us to try to get their attention, find out who they are and change the name for them. Personally, I don't care if they want to be known as JimmyJimJimJimmy but I actually have to use the list to pay them so I need to know their proper name. Registration won't work because it would mean installing something on their computers and .. doctors. Also, they won't register ahead of time because they often don't know until the last minute if they can participate. Obviously I need to adjust a setting but despite research (honestly!) this very simple question's answer has eluded me. Yesterday I joined a Skype meeting and .. wow a screen that asked me to enter my name! Pretty simple stuff, right?