Hi everybody

How could I solve my problem, which is not so complicated, but I am running circles and can not find a solution... I would like to manage installment payment for some of my bills, with fields like Bill, Payment_rate, Rest_of_the_Bill,  The first 'run' is OK, but when I am trying to enter the second Installment for the same Bill, there comes a problem,,, I can not find a way to update the 'rest_of_the_Bill number.

Thank you for any thoughts