IR should not post if GR reversal (MBST) exists

Question

My scenario is this.  I am posting an invoice using MIRO against a PO, in which the GR was received using MIGO and then reversed using MBST.  The invoice will post in this scenario, but I don't want it to.  There isn't a valid GR for this PO since it had been reversed.  Is there any way to block this?  I would appreciate any help/suggestions you can give.  This is particularly dangerous with our EDI transactions.

Answer 1

Yes, when the material document is created (MIGO), an accounting document is also created which DR the expense and CR the GR/IR.  However, this accounting document cannot be reversed using FB08.  The error message is "Not possible to reverse the document in financial accounting".  Anyway, the GR is being reversed by someone in the warehouse, not in finance.  When using the transaction MBST, it reverses the material document and creates a new material document that references the old document.  At the same time, it creates another accounting document that DR the GR/IR back and CR the expense.  This document doesn't reference the original accounting document, however, and if you then try to enter an invoice using MIRO, the original GR will appear and the invoice can match it and post to it.  This creates an accounting document that DR the GR/IR, and CR the vendor.  Now, the entries for this PO are as follows:
1st GR:
DR expense
CR GR/IR
Reverse GR:
DR GR/IR
CR expense
Invoice:
DR GR/IR
CR vendor
This leaves the GR/IR with 2 DR and only 1 CR.  I am trying to find a way to circumvent this from happening.  When an EDI document comes in, it will post to this PO without realizing that the GR had been reversed. 
Does anyone know of a way to prevent this?