Hi Ed,
Thanks for reaching out! Attendees who have RSVPed or purchased tickets for a calendar event will not be automatically notified if changes are made to the event. If your attendees have purchased paid tickets using Event Tickets Plus and WooCommerce, you can resend ticket emails with the updated information by locating the ticket order in WooCommerce and selecting the “Resend Tickets” action. However, I’m afraid there is no such action available for RSVP orders at this time. 🙁
If you’d like to have this functionality developed for your site, I’d suggest enlisting the help of a qualified developer, as this type of customization is likely to be fairly complex. We do maintain a list of third-party developers who work with our products and who may be willing to take on such a project!
I hope that helps to get you started here! Thanks again, and let us know if you should have any other questions!