CMK suppliers with multiple sites

Summary:

We are implementing e-invoicing in Belgium and are having an issue with suppliers that have multiple sites.

Content (please ensure you mask any confidential information):

The group has multiple legal entities in Belgium and for the new legal requirement we need to implement e-invoicing. We're using collaboration messaging and want to use one trading partner with the xpath to identify the application partner id. On the supplier we enable the B2B communication and add the trading partner with the application partner id.

This works fine if the supplier has only one site assigned. When we have multiple sites because the supplier is used in multiple business units, all invoices are imported into the first business unit that was assigned. All sites have the same application partner id. This id is the VAT number as it is the unique identifier of this supplier.