DS 3.6 is starting nursery school. He had his home visit and we discussed all his allergies (dairy, soya, beef). They then put up notifications around the kitchen. Good. We discussed that the only time DS would be exposed to milk would be at milk time and he would be closely supervised.
We did the stay for an hour yesterday and today. One parent brought in yoghurt into the classroom and was feeding their child. She was asked to take it out.
But then DS was asked by his key worker to come and have a carton of milk

I replied that he was dairy allergic, that clearly she had forgotten, but that I will need to re think him going to nursery school if she forgets his dairy allergy on Day 2 with me there.
What do I do?