I had a question from an Outlook.com user who shares the calendars with other family members. When the accounts were on the old server, the calendars were editable in Outlook but aren't on the new server.
The family shares Outlook.com calendar (new server) with each other but in Outlook 2016 I can only view the shared "Outlook Mail" calendars. I cannot add new events to them. They are all read only.
Correct, at this time, the shared calendars are read-only in Outlook. If you attempt to create a new item on the calendar or edit an existing event, you'll receive this error message:
You don't have permission to create an entry in this folder. Right-click the folder, and then click Properties to check your permissions for the folder. See the folder owner or your administrator to change your permissions.
This includes the Family calendars enabled in Microsoft accounts. They are editable in Outlook on the web and in Mac (because Mac uses web servers to sync), but not in Outlook on the windows desktop. This is because you can't actually assign permissions to the calendars.
Outlook.com supports sharing calendars with editing permissions, however, the recipient needs a Microsoft Account for their address. If the Outlook.com account associated with the Microsoft account is added to their Outlook profile, they will see the calendar in Outlook (under Other Calendars group). If the user shares the calendar from the Outlook.com web interface and the other person accepts it from the outlook.com web interface, it will be added to Outlook desktop and sync to all devices. But, at this time, it is not editable in Outlook windows desktop.