Merging of Invoice for delayed item shipping discount fee is not getting applied.

Hi Gurus,

I have scenario where in while creating a sales order for items shipping fee is charged , whereas when a particular line item

is manual shorted delayed shipping fee is getting charged. and after that we are raising another sales order for FOC orders

where there is no shipping fee concept involved in it. when we are merging and doing delivery for both the orders they are working fine

But when doing invoice(billing) by merging suppose for delayed item shipping fee discount is not getting applied at billing level

what could the reason for seperate orders for billing shipping fee is getting applied , whereas when merging a sale order with FOC that is where issue occuring delayed shipment fee discound has to be applied

Needed your suggestion whether any configuration need to done or else any ABAP program needed to be modified.