How to update delivery quantity via BAPI?

In my business scenario the WMS system post GI of deliveries and send the info to SAP.

If WMS post GI for the entire quantity ==> no problem
If WMS post GI for quantity < delivery quantity ==> problem.
I should update the delivery quantity (LIPS-LFIMG) and then post the GI.
I tried with WS_DELIVERY_UPDATE and with BAPI_OUTB_DELIVERY_CHANGE without success.

Have you ever faced this case?

Solution

I solved it by calling BAPI_OUTB_DELIVERY_CHANGE with the following mapping:

LS_HEADER_DATA-DELIV_NUMB = <FS_LIPS>-VBELN.
LS_HEADER_CONTROL-DELIV_NUMB = <FS_LIPS>-VBELN.
LV_DELIVERY = <FS_LIPS>-VBELN.
LS_ITEM_DATA-DELIV_NUMB = <FS_LIPS>-VBELN.
LS_ITEM_DATA-DELIV_ITEM = <FS_LIPS>-POSNR.
LS_ITEM_DATA-MATERIAL = <FS_LIPS>-MATNR.
LS_ITEM_DATA-BATCH = <FS_LIPS>-CHARG.
LS_ITEM_DATA-DLV_QTY = LS_VBPOK_TAB-PIKMG. ==> new quantity
LS_ITEM_DATA-DLV_QTY_IMUNIT = LS_VBPOK_TAB-PIKMG. ==> new quantity
LS_ITEM_DATA-FACT_UNIT_NOM = <FS_LIPS>-UMVKZ.
LS_ITEM_DATA-FACT_UNIT_DENOM = <FS_LIPS>-UMVKN.
LS_ITEM_DATA-CONV_FACT = <FS_LIPS>-UMREF.
LS_ITEM_DATA-GROSS_WT = <FS_LIPS>-BRGEW.
LS_ITEM_DATA-NET_WEIGHT = <FS_LIPS>-NTGEW.
LS_ITEM_DATA-UNIT_OF_WT = <FS_LIPS>-GEWEI.
LS_ITEM_DATA-VOLUMEUNIT = <FS_LIPS>-VOLEH.
LS_ITEM_DATA-SALES_UNIT = <FS_LIPS>-VRKME.
LS_ITEM_DATA-BASE_UOM = <FS_LIPS>-MEINS.
LS_ITEM_DATA-STOCK_TYPE = <FS_LIPS>-INSMK.
LS_ITEM_DATA-VAL_TYPE = <FS_LIPS>-BWTAR.
LS_ITEM_DATA-INSPLOT = <FS_LIPS>-QPLOS.
LS_ITEM_DATA-VOLUME = <FS_LIPS>-VOLUM.

APPEND LS_ITEM_DATA TO LT_ITEM_DATA.

LS_ITEM_CONTROL-DELIV_NUMB = <FS_LIPS>-VBELN.
LS_ITEM_CONTROL-DELIV_ITEM = <FS_LIPS>-POSNR.
LS_ITEM_CONTROL-CHG_DELQTY = 'X'.

APPEND LS_ITEM_CONTROL TO LT_ITEM_CONTROL.