Changing webinar time doesnt change the calendar for attendees

We have attendees registered to attend a webinar and we may have to reschedule the date/time. However, if we do that, we found that it will send an email to attendees letting them know it changed, but not update their calendar. We have found this the case for google calendars.

AND -- if they add the rescheduled event to their calendar, they end up with both events and its confusing to know which is the real one. Please advise if there is a fix for this!