We have a requirement here to make a substitution to the XBLNR_ALT field for Italy. We already set up all the necessary and everything is working perfectly for the ODN piece.
The requirement is now to create a substitution for other document, some kind of Selfbilling process where the user needs to enter the document number being created and this document needs to flow in to the BKPF-XBLNR_ALT field. We have tried an FI substitution, which helps perfectly when the document is being created using an FI tcode such as FB01 or F-02. But if we try to created the document using the FM: BAPI_ACC_DOCUMENT_POST or IDOC_INPUT_ACC_BILLING it is not getting substituted. I can debug the substitution and it is possible to see it is getting substituted succesfully, but at the end BKPF tables doesn't get updated.
Any tips will greatly appreciated.