Gorilla Expense can change the vendor config setting to allow the user to enter a particular vendor entry that is not in the list. But there are three things to note (point 3 is a remote possibility)

1) First thing is that the users will have to reinstall the app on the phone to reflect it (on the web it will get reflected instantly).  Such system settings get updated only during an install / first time login and are not currently updated during each login. When they re-install the app on the phone a "+" icon will be available on the top right corner of the vendor list screen (please see attached vendor list screens of the web and mobile respectively).
2) By default the added vendor is stored in capital letters. We can disable this feature if you would like, in which case, the system will rely on the user to use capitals where required (not recommended as user tend to be a bit less careful especially on the phone)
3) A vendor added by a particular user on the phone or on the web will be available to all users on the web instantly. On the mobile app though, other users will have to go to Download Masters-> Vendors and download the latest ones from time to time. This is not a required step as we do have a mechanism in place to identify duplicate vendors entered on different mobile devices and not create duplicate vendors in the database when an expense is uploaded via the mobile. Having said that there is still a remote possibility of almost duplicate vendors being created (for example, user 1 creates Holiday Inn on his mobile device and User 2 creates HolidayInn also on his mobile device)