The thinking behind the question is based on 3 years working at APC. Granted, it was over 16 years ago and I was a different cap badge, but the principle remains the same. To be considered for promotion to WO1, you must be selected at a Board held annually at the APC. If my memory serves me well, the WO2 to WO1 Board is (or was) chaired by the 1 star Head of Arm (now OF5), with a couple of COs, SO1 Soldiers, and the Corps RSM making up the 5 Board members, with SO2 Soldiers as the Secretary.
If she was selected on this type of Board and didn’t pick up her appointment because of a career ending injury, I suspect she was eligible for financial compensation rather than ‘Honoury’ retrospective promotion, which is not something I’m aware of.
I can say that I was involved in a Compensation claim for a R Signals WO2 (male) who was selected by a Board for promotion to WO1. He was involved in a serious motor cycle accident and medically discharged from the Army before he took up his (RSM) appointment. He was (is) a good egg and had excellent potential.
The Corps supported his Compensation claim (based on missed promotion and potential LE Commission) and he was awarded a substantial pay out.
Did your friend receive similar compensation?