This will show you how to add another calendar to your Outlook calendar.
1. In YOUR Outlook right click on "My Calendar".
2. Click on "Add Calendar".
3. Click on "From Address Book".

4. Double click the person you want to add their calendar.
5. This will add their name to the spot below.
6. Click "OK" to confirm adding that calendar to your view.

Once you do this you should be able to scroll in your list of calendars and check the box next to the name to see their calendar.