Thanks for everyone's comments !
Is the an easy way to tell if a TT file was generated independently or imported from a previous year ? Long story but this person did not file all the returns "in order" - some years were skipped, done later, real mess. We have what we think are native TT files from each of the years (and outputted PDF).
Look for way to confirm if, for example, 2010 return submitted was started from 2009 import (or started independently). There's a lot of transactions and complications - so it is not obvious from looking at submitted PDF that "import" was used to initiate each year.
