In Microsoft Outlook you can view two calendars ‘side-by-side’ or overlaid to look like a single calendar.
Select two calendars from the left-side pane of a Calendar view. Choose from ‘My Calendars’ or ‘Other Calendars’.
The selected calendars appear ‘side-by-side’ in different colors.
Overlaid with other calendars
Click on the little ‘left arrow’ button on the calendar tab to switch to overlaid mode. Now the calendars appear on top of each other but still colorized so you know which items are from each calendar.
An .ICS link
One popular way to add any extra calendar into Outlook software is a web link which ends with .ics
.ics means it’s an iCal or iCalendar format file. It’s a plain text file which Outlook can convert into a calendar and update that calendar regularly.
The .ics link looks like this, it’s a standard web link (http / https ) and ending with the crucial .ics.