Add events list (calendar) in folder

Did you know that you can create overlays to point to views in the same calendar and therefore don't need to create separate calendars for the data? - It all depends on how you categorize the data.

I've used the "Category" column before in a calendar and then created views to filter each category. The main view I build the overlays and then filter out everything by doing Category = nothing so duplicates don't show up.

You could use Microsoft flow to copy calendar events to a specific folder

https://powerusers.microsoft.com/t5/General-Flow-Discussion/Flow-to-coypy-events-from-one-calendar-to-another-calendar/td-p/91960