German student in Australia for 9 months suffering bulima?

I have a German student 16 years old arrived in Australia at 59 kgs ate like a pig and maybe went to 63-65kgs in first few months.Stated jogging andeating less than our 7 year old daughter weighed before xmas and was 53kgs. Informed school, started seeing counsellor, her parents whom are both doctors in Germany and also mentioned she has alot of phscological problems arrived from Germany for 3 weeks over xmas break and of course sheate normal etc, now they have returned but now the student is 48kgs and I believe she is vomiting after meals even though she not admitting this and seems as though she is lying so as not to be sent back to Germany wtail between legs. Do I take a stand and say I am fairly sur she is vomiting after meals even though not admitting or put up with her till April and let her folks sort out when home even though they know the facts and seem to be in denial too!!