Process after response means that you will be able to process an Invoice furhter in the process. i.e. print and post it after you have received an accepted response. the Invoice remains in Preliminary status until you have received the accepted response. 

Automatically process acepted invoice means when you receive an accepted response the Print and post step will be triggered automatically if you have set this parameter to yes. If paramter is not enabled you have to print and post the Invoice manually.  

I don’t fully understand the design. When you write “an accepted response” I understand it as the response must be succesful. In this case I delibrately send an invoice with a failed response:

But the invoice still gets posted, not prel anymore

In this case I cannot update the invoice and resend in, it has gone to far in the process.

This is my set-up:

When it says “Process after Response”, I understand it as “process after successful reponse”, but it does not work that way - if invoices are processed from prel to posted regardsless of response. Then it is impossible to adjust a faulty invoice and Resend it

Update: I it actually works to update the invoice and correct and resend even if it has changed number from prel to CD. I can update it and get a positive response.

When Process after response is enabled, you will get the final invoice number when sending the Invoice as the authorities requests this. Although the Invoice status should still remain as Preliminary and you will be able to modify it if you get a rejected respose.