Did you tried this BAPi
BAPI_RESERVATION_CHANGE
You can change the following fields in a reservation item:
Storage Location (field STGE_LOC)
Batch Number (field BATCH)
Quantity in Unit of Entry (field ENTRY_QNT)
Requirements Date of Component (field REQ_DATE)
Item Text (field ITEM_TEXT)
Goods Recipient (field GR_RCPT)
Unloading Point (field UNLOAD_PT)
Set the 'Quantity is fixed' indicator (field FIXED_QUAN)
Set the 'Goods movement for reservation allowed' indicator (field MOVEMENT)
Set the 'Item is deleted' indicator (field DELETE_IND)
Set the 'Final issue for this reservation' indicator (field WITHDRAWN)
Bluesky
