After creating a trip, add co-travelers to it via the Settings icon on the top navigation bar. Click on “add co-traveler” and specify the email of the co-traveler. The person will receive a notification of your invitation to see and edit the trip.
Whenever a co-traveler adjusts the trip, you can see the changes by clicking on the Notifications icon on the top navigation bar.
To remove a co-traveler, click on the Share icon on the top navigation bar, select Manage Co-Travelers, and click the X button.