Un-reserving stock (inventory) in AX 2012

I have a need to un-reserve all sales order items that have not been included in a shipment by a specific cut-off date in December

I understand that my user base are firstly going to delete any shipments that are not complete (Sent), delete any output orders at "Created" stage. That leaves me to develop an AX job to amend the reservation status of the affected items. I believe that I need to scan the InvenTrans/InventTransOrigin tables for lines with status (StatusIssue::ReservPhysical & StatusIssue::ReservOrdered) and set the qty to '0'

In addition to the un-reserving, the script should document the original reservation details, such as qty as the next step is to develop another job to restore the reservation status at the end of December, ready for business as usual on the 1st January.

Does anybody have any advice, or guidance? Any help would be greatly appreciated