How to Prevent the PO Total from Exceeding the PR Total While Allowing Changes Between PO Lines?

We have a requirement to prevent the total Purchase Order amount from exceeding the total approved Purchase Requisition amount at the header level.

At the same time, the customer wants buyers to have flexibility to change or redistribute amounts between the PO lines , provided that the total PO amount does not exceed the approved PR total amount.

Example : PO Line Changes Within the Approved PR Total

The approved PR contains the following lines:

Line	Description	PR Amount
1	Hardware	SAR 600,000
2	Software	SAR 300,000
3	Professional Services	SAR 100,000
Total		SAR 1,000,000

During PO creation, the buyer needs to redistribute the amounts as follows:

Line	Description