I called special needs (thanks for the suggestion, I had never needed or heard of such a service.) They said the do indeed deal with this all the time. I said we aren't just talking a vegan diet here but she assured me they can special order and they will special cook her meals to order. She also mention talking with the staff in the MDR. And I guess there is a form you can fill out on booking. Good idea to talk to the cook too. We took her to a very high end resort in Thailand and the head chef came out at the start and went over her needs and then personally cooked all her meals. But then that's what you expect out of a $1000 a night resort. Just not sure if they can make good on this.