AMS route
It's not a Border Force issue that the flight is going to EDI. Dundee coverage is actually the responsibility of Border Force in Aberdeen, but officers from ABZ & EDI have been providing officers. Also staffing wise Border Force demands reduce at this time of the year as flights reduce at Edinburgh or indeed Glasgow. Border Force Officers are a mobile grade and can be deployed from any Scottish ports, as travel to Dundee is within a 10hr shift.