If another user grant you the right to see her calender in Gmail, you can merge her calender with your.

Steps to view another user’s calender in Gmail

  1. You need to get another user’s permission to see her calender.
  2. Log in to your Gmail account.
  3. Click on Calender at the upper left hand corner. 000 - Access Google Calender
  4. Enter calender’s owner’s Gmail address in other Calender area (as shown in the picture below) 001 - Enter Calendar Owner email