Transaction Notification Stored procedure that has exceptions

Dear Experts,

I am currently working on a transaction notification for a client. The following are the exceptions that the client wants incorporated with the Transaction Notification:

1. You cannot add an AP Invoice (Items) without a Goods Receipt PO.

2. You cannot add an AP Invoice (Service) without a Goods Receipt PO However,

3. Number (2) above has exceptions and these are:

- You can generate an AP Invoice without a base document (Good receipt PO) for a group of vendors in the vendor group 'INTER-COMPANY SUPPLIERS'

- You can generate an AP Invoice without a base document for another vendor who is not in the above vendor group and has the supplier code 'S00009'.

Kindly help in generating the above code.

Regards,

Pascale.