Dear Patrik
As an Access Point Provider (APP), you have the ability to initiate a Lookup that leverages the Party's TIN or Invoice Reference Number (IRN).
The Lookup endpoint returns metadata, including the recipient’s registered APP and Participant ID (for those registered on the PEPPOL network), which serves as the routing information for invoice transmission.
The Accounting Customer Party section is optional for B2C invoices, as these transactions involve simplified invoicing that focuses on reporting rather than detailed information exchange between parties.