Most schools keep their application period open after the lottery is run. If you're still accepting applications, you can continue to apply on behalf of parents even after your lottery is run. Here are the steps:
1. Be sure to check on your Academic Calendar that your "Application End Date" is set into the future. If this date has already passed, then you won't be able to apply on behalf of parents. (Go to Settings > Set up Calendars and Dates > Academic Calendar)
2. Apply on behalf of parents as you normally would (Admissions> Create Applications> Sign up a Parent). Be sure to answer all the questions on the application for them, to be certain their applications are automatically assigned the right priority.
3. Then the system will automatically add them to the Waitlist at the bottom of whatever priority group they are in. So no need to apply any waitlist numbers.