When creating a new third party reservation, the system will allow a user to book if available or overbook a room type(after presenting a warning), even if it is not available.
There are user permissions available, if you would like to turn off the feature of adding a third party reservation or the option to allow third party overbookings.
Navigate to Users - Roles - Edit Role - Under Reservations
Both user permissions are active by default.
If active, it allows the user to create any third party reservation and even if it creates an overbooking.
If deactivated, it does not allow user to select that room type when creating the reservation and/or prevents any overbookings through third party reservations.