Paid webinars

Does anyone have a suggestion on how to register someone for a paid webinar with no fee? For example, it would be nice to be able to allow some people to attend complimentary but unless they pay, they cannot register themselves. Currently, I have been adding them as panelist and then changing the status to attendee when the webinar starts, but this is cumbersome. Also, I learned that while in practice mode, if I change the person to attendee, they are pushed to a waiting room but can still hear the conversation of those in practice mode.