If you already have a list of participants for your Meeting you have the option to import the list instead of adding them name by name.
Sample CSV (Comma Separated Values):
To attach a .csv file go to Advanced options (either when you create a new Meeting or edit a Meeting) and click on Participants.
At the bottom click on Browse and then select your .csv file. Then click Upload.
Once you have made changes remember to save them by clicking on Add to schedule.