Eliminate Change Reason Required when overriding modifier rate on order line

We regularly override the modifier rates automatically applied on sales order lines. When doing so we are then forced to enter a change reason. We use the "Manually Applied Adjustments" reason ALWAYS. Since we cannot change the CHANGE_CODEs lookup to restrict the list to just this one, we want to try to stop the Reason Required field from coming up altogether. I reviewed all of the processing constraints and there doesn't seem to be one that controls the Modifier Rate.

Does any one know what is controlling the Change Reason Required when overriding the modifier rate and how to turn it off?