Financial institutions sending CCD files to FRB

We are a credit union that would like to begin using ACH to make vendor payments. I've been testing the process using the CCD+ file format. As a financial institution ourselves, our bank is the Federal Reserve and when we send them a test file, it is rejected due to having the vendor's bank DFI in the Trace field of the Detail Record line. The Fed is indicating this field should be populated by our DFI number.

Oracle is telling me there is no way to make this happen without a customization. I'm having a hard time believing that this should be the case, given the length of time the electronic payments via ACH process has been used. Does anyone have any experience with this, particularly in a banking environment?