Legal Hold question: Bulk import of custodians for new custodian notice

Clearwell version 7.1.2

I have a case that will require over 500 custodians to be added to a custodian notice.  My entire Active Directory is imported in to my employee list, (50K+.)  Currently, when I create the notice and click "Add Custodians" my only option is to select each custodian separately and add them to the notice.  Is there a way to import the names into the custodian notice using a CSV?

With over 50,000 users in my environment, searches for every custodian can be time consuming.  Needless to say, adding 500+ custodians one at a time is not a pleasant prospect.