This hmmmmm - The last time round it was someone's son who wored the cheapy plimsolls and their daughter who liked Vans.
Why not ask the children's mother what the school policy is, and (if she was the poster who asked last time) what answers she got from the grans on here?
As I remember it, she continued to post variations on her original question for a long time, so she has plenty of answers to choose from. For such a long time, in fact, that it became obvious to everyone that she wasn't really interested in solving the problem.