Adding attendees
Hosts, delegates, and moderators can add attendees to a meeting after it starts. For example, you can add an attendee who wasn't invited to the meeting but has expertise that you or other attendees need.
To add attendees
In the left control bar, open the More options menu ( ), then choose Add attendees.
In the Add attendees dialog box, select the attendees that you want to add, then, choose Add.