... then we could transfer all those planned events to the mainWell, at the bottom of the planning calendar pages is a blue "Subscribe to Calendar" button. Clicking on that will give you a link to a page containing that calendar's events in iCalendar (.ics) file format.
But that's only half an answer, because I don't know of a way to then import that file into the main calendar.
Likewise one by one. In each event you can download it as an .ics file, but then there's still no way to import them into the main calendar.
More Help: https://groups.io/g/GroupManagersForum/wiki
Even More Help: Search button at the top of Messages list