I didn't know where to post this random idea/headcanon that I have so here we go.

So I was posting this for Cee's birthday party. It's not the first time I'm thinking that there's possibly wizards who offer services in space altering charms. They can make your tiny ballroom fit a stadium worth of people, make Hermione bags, these sort of things.

My thinking is that this is a complex form of magic which probably doesn't last for very long if it's performed in actual spaces, and it needs to be maintained for its duration. Hence why your character would hire these service people, so they can be at your ball and ensure that the big ballroom doesn't suddenly become small and crush all in attendance inside. (but hey? new Charming Tragedy idea!)

I'm thinking that this could even be something that you need to gain a professional certificate from the Ministry to do it, and maybe pass an exam of sorts.

And of course, there could be a WC family that specializes in this business

Let me know what you guys think!