Is your feature request related to a problem? Please describe.
I subscribed to an external read-only calendar, only a few of which events I will attend. When I am planning to attend one, I add an event in my regular calendar, but have to copy over the details manually.
Describe the solution you'd like
A "Duplicate" option in the event edit menu of read-only events, just as for events in editable calendars. Choosing this would either switch the calendar for the duplicate to the default one, or block saving the duplicate until you switch it to a writable calendar.
Describe alternatives you've considered
No response
Additional context
Similar to this (editable event): 
Here (read-only event): 
Is your feature request related to a problem? Please describe.
I subscribed to an external read-only calendar, only a few of which events I will attend. When I am planning to attend one, I add an event in my regular calendar, but have to copy over the details manually.
Describe the solution you'd like
A "Duplicate" option in the event edit menu of read-only events, just as for events in editable calendars. Choosing this would either switch the calendar for the duplicate to the default one, or block saving the duplicate until you switch it to a writable calendar.
Describe alternatives you've considered
No response
Additional context
Similar to this (editable event):
Here (read-only event):