Advice on invoice model

I’ ve drawn this model about the payment of electronic invoices in Italy. In this case, the model invoices three actors:

  1. Supplier, who produces the document in xml
  2. SDI, an electronic system that checks xml tags of the document
  3. The company, that receives the invoice and checks its congruity before proceeding with recording and payment. The information for checking activity are preserved by two erms, docspa and SAP, so both of them are invoiced in the process.

The invoice must be registred by the company even if it is wrong. E.g., if docspa detects that gross value is wrong, the invoice does not return to the supplier, but goes on and is every way recorded by sap. (in the end the supplier will produce a note credit, with another process that I have not drawn here).
How can I model this case? Connecting “Produces ID document in SAP” with XOR gateway, it seems that only the outcome of this activity is important for deciding the way of the process… Maybe I can group the check activity in subprocess or using group element?

Since this is a non-trivial question about BPMN modeling I’d recommend asking it in the Camunda forum as it is much more likely that someone can help you.