Hi Oscar,
In the invoice you should be able to see the header partner functions.
So that's not normal.
May I ask what is the business reason not to stick with standard partner functions in billing?
IMHO Billing should be a more or less automatic process in SAP based on delivery data (delivery based billing) or credit note data (sales document based billing), therefore it does not seem to be a good idea to have the RE partner editable in the invoice.
In general the partner function in billing should be determined from original document (sales order or credit note) and modified there in case of needing to do it.
Best Regards,
Franck
