ATCWatcher, have to correct you. Unless things have changed radically since my day, the ATC FPL is seen in its entirety by the departure aerodrome ATC who, as the form tells them, are not required to send the supplementary information to other ATC units along the route. However they are required to pass it to other ATC units if asked for it in the event of an incident/accident anywhere along the route involving SAR and its Incerfa/Alerfa/Detresfa phases. Hence the need for the dep ATC to have the supp info to hand for as long as necessary.