oh they won't support at all - they are right, you see? they cling to the fact that gf/cf hasn't been proven as such, and has little medical backing, rather than taking on board anything I say.
I totally get what you mean re: the cupcake.
dd1 has a simple instruction on her food list: gf/cf, no citrus, and everyhtign else to be "real" food (ie an actual pear, rather than ridiculous fruit sticks or whatever they are called. fresh rather than tinned, etc etc)
and they gave her jelly.
they then witnessed the fallout from that (dd1 silent and passive at school turned into screaming biting monster) and still they don't believe
and when I looked absolutely shattered later that week (sleep went to pot as she dealt with the crap from the jelly) and asked why, and I wrly said "oh she's not sleeping very well - she gets like that after diet issues" and they just laughed it off and told me all ASD childrne have sleep issues, and i was lucky that I didn't normally have issues...
the fact that they won't even let me send in suitable alternatives is the bit htat grates - I even asked for a copy of their menu plan so i could send dd with the same thing but ok for her, but it's not allowed at all. and apparently dd1 is the one with control issues
still, she won't be there much longer if we have our way, so hopefully will soon be a thing of the past.