We just returned from our second
Disney cruise - my son also has a severe allergy to dairy. Our first cruise was 9 years ago when he was 3; our most recent was the 7/9 11 day Med cruise. I loved how Disney took care of him 9 years ago and I can report that things were even better on this trip.
As others have noted, the head server will talk with you about your allergy. Kapoor brough Michael the next day's menu during dinner each evening to allow him to select what he wanted and to ensure that it would be available. Dairy allergies often make dessert options very one note - soy ice cream; but Kapoor asked Michael what he wanted and once Michael said "chocolate cake" they provided a small chocolate cake with chocolate sauce and fresh berries. It was wonderful! Disney also provided fruit crumble/cobblers. For his entrees Michael had pheasant, Cornish game hens, duck, chicken and lots of his favorite steak! Kapoor even arranged to have special dairy free pancakes, sauages, bacon and hash browns available for him every morning with Chef Erick.
In the past I've always been discouraged from dining at the buffet due to cross contamination concerns. This cruise we needed to dine at Topsiders early on and we met Chef Serghei - he went above and beyond to provide Michael with safe, excellent options at the buffet. He knew what Michael likes and didn't like - made him special stir-fries, potato and vegetable options - too much to go into, but he was wonderful.
When Michael was three - he ate a lot of filet mignon, french fries, vegetables and fruit. All dairy free - all prepared especially for him.
When I returned from our wonderful Med vacation people asked me what I liked best - my first reaction was the fact that I could enjoy the vacation and my family without constantly worrying about my son's allergies. Any parent of a child with food allergies knows just how valuable that is.
You can assure your friends that DCL will absolutely take care of their son's allergies.