Protect Unit Price but Allow Price History update

We are currently upgrading from A7.3 to A9.3 and one of the "wish list" items is to not allow users to override the unit price directly on the order, but to use the price history window to update using a manual adjustment schedule. This is required so that rebates and accruals continue to be applied against orders where the price is "overridden". We have tried setting processing options 33 & 35, but when 33 is on price is protected, but so is the price history window values. 

I saw that in the latest E1 there is functionality to handle manual overrides and rebate/accrual application, but do not see the same fields in A9.3.