Add back Open Calendar option
In the old OWA you could add a colleague's calendar by right clicking a calendar group and then selecting "Open Calendar". This would allow you to search for your colleague and then add their calendar to your calendar group in the sidebar. This is an integral feature for team based, global companies in order to keep track of your colleagues' time and location.
Thanks for your feedback. The ability to add calendar from directory is in the OWA Beta. Click on the “discover calendars” link in the left panel of the calendar. In the discover calendars dialog, select import calendar from directory.