How to enable Subscribed Calendar to be in read/write mode? As today, any Subscribed Calendar is added as Read Only to the iCal Application

to confirm that. just double click in a day with the subscribed calendar selected and you will get this annoying popup message



What should I do to enable read/write mode into the subscribed calendar, as it supports both ways (I created the URL and works great with Thunderbird w/Lightning)

Problem also comes that in iPad/iX happens the same situation, and all I wanted was to be able to create and edit events to by calendar
The owner grants &amp; controls read / write access. You'd have to ask who owns the calendar.