The cadet force in question hasn't been mentioned but assuming it is the Air Cadets but I think the others are slightly different. I'd have to disagree, as I've seen cases where air cadets have joined up with previous experience before progressing onto being a Staff Cadet. One even re-joined 17 years 11 months with less than a year of experience.
It really is a hard one to comment. It will be best heard from the squadron staff who will be able to say whether or not she will be able to be supported and whether she meets the criteria to stay on based on her previous experience be it academically through the training etc. Speak to the specific squadron staff for the best guidance.