In Odoo 15, when creating an invoice using the "account" app, you have the option to generate an EDI document (XRechnung) through the "Import/Export electronic invoices with UBL/CII" module (account_edi_ubl_cii). Additionally, with the attachment_indexation module, the PDF file for the invoice is integrated into the XML. However, the problem arises when trying to include custom attachments (also in PDF format), as they are currently being ignored. In the XRechnung format, these attachments should be part of the AdditionalReferencedDocument section (specifically, fields BT-122 and BT-123), containing the document in binary format within the XML file.
Is there a way to configure or make adjustments in Odoo 15 so that custom file attachments for an invoice are considered during the XRechnung export process?