Note :
1) Enter information for first kid and say pay now. You will be routed to the payment page. Go back to the information page again and enter the information for second kid and say pay now. In the payment page, you should now see the names of both kids with correct total. Make a payment and you will receive proper confirmation.

2) An alternate way to do this is, enter the information for first kid and say pay now. You will be routed to the payment page where you will complete the payment. Then go back to the information page, add information for the second kid and say pay now. Again you will be routed to the payment page where you will complete the payment. In both the cases, please make sure that the amounts mentioned are correct.