Demand plan approval for few items

Currently Demand plan approval is available at plan level. If demand plan is approved, it copies 'Final Shipment Forecast' meaure to 'Approved Final Shipment Forecast'.

Our Requirement is to approve forecast for few items while keeping other item's shipment forecast for review. Supply plan input is 'Approved Final Shipment Forecast' measure so once plan is approved all the new forecast numbers will flow to Supply plan. We want to continue using previous approved numbers for some of the item.