Yeah, I think I am out of luck, there is too much data to do anything like that @JeffSchwenk I thought of using exchange, editing the csv in the middle, but there are hundreds of thousands of postings in their gl detail and it would be too risky, they would never authorize it. I am afraid they are going to have to live with the data missing and just know they are getting it from this point forward.
Good point @BillPfahnl Are the account keys the same when a company has been copied to a test? That would mess it up as well.