Customize "Save" button based on data in form?

[JMacFeegle]

I have a list of resources than can require confirmation to book or not in table Resources.

Bookings/reservations are entered in table Calendar.

When making a new calendar entry, or "reservation", I want the "Save" button of the form say "Request", if the resource about to be booked requires confirmation.

Usually I'd do if([Resources].[Confirmation required]=TRUE;"Request";"Save"),  but since the localization options are not evaluated in the context of a row, this obviously does not work - or is there a way?