Well, I've learned something new today.
However, I'll still stick with my 'direct' approach as the Airways Reporting points on the FIR boundary are up to 18 miles apart and precious few are on the routes I regularly fly.
For me, it's easier to create a user waypoint at an arbitrary point on the boundary (just touch it!); I've never been asked for lat/long details or name of a specific point on the boundary, just ETA. With Products like Sky Demon, one doesn't even need to know the lat/long as it populates the FPL automatically.
Onwards and upwards...
