It’s contagious from a few days before spots even appear, unfortunately if they’re going to catch it they’re going to catch it and soft play is a breeding ground for germs. Even nhs guidelines say if they’re well in themselves with it they can go to school nursery etc you don’t need to isolate them from others. If they do catch it just keep and eye on their temp, ensure their not in pain especially in their mouth and keep promoting lots of fluids x
Normally it is spread through bodily fluids. My oldest recently brought it home from school and my youngest didn’t even get it.
On purpose? How wicked of her.