DS2 and a friend hatched a plan for the friend to come for tea. They put me on the spot and I said of course it was OK, provided his mum agreed.
I spoke to Mum (for the first time) and gave a date that was suitable for us, if she was happy with it. A week later he came for tea, was good as gold and his older sisters came to collect him at the allotted time. I hadn't seen Mum again in the meantime.
I'd never spoken to Mum before because she collects a number of children and isn't usually at DS2's classroom door. The child is also fairly new to the school.
Anyway, everything was fine, it just occurred to me that I'm not sure what I'd have done if the plan was for DS2 to go to their house, as I don't know the parents at all.