How to update Sales Order line EFF value in AR invoice Unit selling price

Summary:

We have requirement to update the sales order price after the ship confirmation has happened in 3rd party application. We can know the actual material i.e. Lot number only after shipment and based on that we need to update the SO line price. But this is not available as standard.

We are thinking of storing this price in Sales order EFF and send these values to AR in the standard field Unit selling price through service mapping. We need help to build this service mapping.

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