As per the actual system behavior, we have 2 different ways to update the Requested Ship Date for 2 different purposes on Sale Order:

1. If we need to specify the Requested Ship Date for each sales line, we need to adjust the date from Line details then confirm sale order, we have nothing to do with the header here.
2. We can update the header to apply the Requested Ship Date’s change to all the lines belonging to that Sale Order.

For specific business requirement, customer want to have the change in Requested Ship Date on the header without override all the previous sales confirmation journals as changing Requested Ship Date in Line Details could be time consuming for a large quantity of sale lines.

We would like to seek for development that this business requirement could be met when the update on Requested Ship Date from the header does not override the previous sales confirmation journals.