it may be that they have a policy discouraging such developments.

But my instinct is to be paranoid on this - what's even a young adult male doing getting invited round to play by my 8yo? It shouldn't be an issue, but in the world as it is today, it raises questions. Having said that, I've been down that route with several of my YFs, but they were all a lot older. Yes, it's a sad world that we inhabit, but it's a mess we need to live with.