OnNewAppointmentOrganizer triggers Web App

Question

I am creating an add-in that append a fixed recipient to new outlook events created in a particular calendar. Everything works fine in the desktop app with a simple if statement on OnNewAppointmentOrganizer, but on the web app, users are able to select a different calendar from the dropdown menu mid-way through creating their event which does not raise OnNewAppointentOrganizer a second time (or any other event-based feature I could find in documentation).

Is it possible to raise OnNewAppointentOrganizer another time in such a case or is there another solution?

Thank you!