Adding schedule line in GATP result

Question

Hi All,
Requirement is after ATP check using RBA if the order line is filled less than 100%, add a schedule line for the un-confirmed quantity with confirmation date in future.
I have observed availability check with replenishment lead time (checking horizon) confirms a line at the end of checking horizon and does not trigger RBA. This is undesirable. What is desired is order line should first check for substitute and then confirm the balance at the end of checking horizon.
To achieve this I am exploring, set the material for RBA, let RBA occur. Before publishing the GATP result to ECC, if confirmed quantity is less than order quantity add a schedule line confirming at the end of checking horizon in the initial location at which ATP check was triggered.
Appreciate quick input.
Many Thanks,
Bijit

Answer 1

Thanks Michael and Alhad,
Approach evolved:
Don't use checking horizon, use 'Remaining quantity" field in check instruction, select - "Create Remaining Requirement for Source Location Product". This adds additional item for the unconfirmed quantity but with no confirmation quantity. Then use BADI /SAPAPO/IF_ATP_REQ_ITEM_CONF to change the confirmation quantity and the date.
This is working fine for only product check and RBA. But not working for allocation check +RBA and forecast check + RBA.