How to set approval rule on total manual adjustment value

Hi Team,

We are setting up approval on order management, we got a requirement from the client to setup approval based on the total manual adjustment done on the sales order. We tried setting up approval on manual adjustment value on approval rule. We found that with that if we are applying manual discount on the sales order with different value on different order line, the approval rule is triggering the approval for the largest manual adjustment value in all the order lines instead of taking the total of manual adjustment value if all the order line. Please guide and help us