How to Derive Discount list as per sales order date

Hi,
In our project we implemented the attached white paper, where the system drives the pricing strategy based on the Order Date of the sales order.

Although the price list is pulled based on the Order Date, the discount list is recalculated on every revision.

For example:
An order was created on 10-Dec-2025 with a 10% discount (the discount is derived automatically based on attributes).
The discount list was later changed on 1-Jan-2026 from 10% to 20%.
When the original order was revised on 7-Jan-2026, the discount was recalculated and changed from 10% to 20%.

We would like the effective discount list to be derived from the