Event Registrants Custom Fields - Apply to multiple events

When in Settings - Event Settings - Custom Fields, it would be great when creating or editing a field if there was a way to apply it to existing events.  It's super-tedious going through 96 events to add an Event Registrant textbox.

This should really be available for all places you can add to an event, such as event categories.  It would really speed up things for the admins.