My DD went to the cinema with a group of friends (13, 14 year olds). I bought all the tickets as they wanted to sit next each other and an adult had to do an online booking, and the other kids parents paid later on. We usually do that way and it has worked. However one extra child randomly joined them after school today, and asked my DD to pay for her ticket, which my DD did. It is not about the money but I am not really sure how to approach these kind of situations. Let DD decide to invite someone or not ( although technically it was "my" money she used without asking). I don't know anything about that child or how the kid went home etc.