Only use this if there was one child that you didn’t pay for in your initial registration.
Cases where you would pay this fee:
• You paid for 0 children at registration and you want to add 1 (0 children -> 1 child).
• You paid for 1 child at registration and you want to add 1 or more additional children (1 child -> 2+ children).
A membership admin will mark the children as paid after payment is received.