How to handle Pegging when reversals of receiving transactions are needed

When Demand is Pegged to Supply, the inventory received is automatically allocated to the Demand when the receipt takes place.  This can make it difficult to reverse a receiving transaction that was performed in error.  Furthermore, it appears that there is no suitable recovery for correcting this once it has taken place.  I will illustrate this using the example of a Sales Order that has been pegged to a Purchase Order.  For purposes of this discussion, assume that the Sales Order is for 100 pieces and pegged to a PO that is also for 100 pieces. 

Consider the following scenario:

• The user receives a quantity of 75 against this PO.  That quantity is automatically allocated to the SO when the inventory was put away.