Billing FOC item - Third Party Flow

Hi,

We have a scenario on third party flow (item category TAS) which have

problem.

The third party is as below

SO -> PO -> LIV -> Billing

1. We create sales order with price

2. We order a free of charge PO

3. Vendor do not invoice us and no LIV can be done

4. We bill the customer

Billing quantity is set to copy the LIV qty in copy control.

However, when the PO is free of charge, No LIV can be done in the case.

As LIV cannot be done, how the billing qty can be copied from LIV?

Would like advice from SAP on what we can do on this case if we reqired

an LIV before the billing.

Regards,

Terry