Trip owner can assign different privileges to every participant of his trip, only those who are participating can be given editorial rights.
Should some one leave the trip, the will loose all privileges to that trip.
To assign privileges the trip owner has to choose "Edit trip"→"Edit permissions", a new page with an overview of available privileges, and the possibility to assign new privileges to participants.
You can add as many, or few privileges as you wish. No privileges is active until you press "Save privileges". Once you've saved the new privileges, the participants will get new menu options, based on their new privileges.