I don't think I could make myself ask for payment from someone so that their child may attend my child's birthday party, especially when it is pretty obvious that they wouldn't be able to afford it. Even if the mother offered to pay for the siblings, I would feel that I should turn down the offer and pay for the siblings' way. After all, it's not a field trip but a celebration of my child's birth...

We always have birthday parties at our house, anyway, so that there are never any additional "fees". The problem is that I set up the party activities, crafts, and prizes for exactly the amount of children that are invited. I always offer to pick up and return the guests to their house. It came as quite a shock to me when one of my neighbors dumped their ADHD grandson (who was visiting them for the weekend) on me. The lady put two dollars in an envelope for my DD and expected me to watch the boy all day. I initially sent him back home (none of the invited guests had arrived yet) but the neighbor sent him back to our house the minute another car pulled into our drive way. I was not about to play ping-pong with the child's heart and let him stay. I would have liked to give this neighbor a piece of my mind, though. Luckily, she moved away