output determination's userexit for billing doc

Dear Expert,

I have faced a problem about the output determination, i have got a requirement from customer, they want to filter the print out in VF31,  if the original doc has been cancelled, they don't want to appear in the VF31,  if they selected the first processing = 1. 

For example -

Billing no         Doc type          Cancel status          Cancelled No

90123000          F2                             X                     90123001

90123001          S1

90123002          F2

In this case, I just want the VF31 that would only print the billing doc 90123002.

As i know the VF31 would capture the data from the table NAST, if it found the record and process status is zero, it will print the record in the process mode - 1  'first processing'. If i want to fulfill this requirement,  I guess that it should be updating the process status to 1. It means if we go to cancel the billing, the original billing should be marked to process status 1 whatever. I have spent a lot of time  but didn't find any userexit for this. Anyone can help ??