The list will need the following Objects:
User Base
...User Detail

The list will also need the following Global Filters:
User Detail.User Created Date is on after (xx/xx/2xxx)

In place of xx/xx/2xxx, enter the first date that new parents would have been added to the system. This may be the day that admissions were opened for the upcoming school year, or the day that Incoming Students and Parents of Incoming Students were uploaded.