Lockbox File - Negative Receipts

We get files from the bank containing Receipt for electronic transfers from our customers.  In this file, we regularly get negative receipts.  We need to upload these negative receipts into Oracle Financials so they would show on the customer statement.  The customer in turn uses this information to balance their accounts.

I'm under the impression that you can't create or upload through lockbox a negative receipt.  In addition, I know that we can create a negative miscellaneous receipt on the screen, but you can't upload Miscellaneous Receipts trough lockbox.

Do you have any suggestion or insight on how we could upload these negative receipts?