When I do ABIP inspections, I look for the latest complete report. Normally, this is the last Biennial reort. But if a complete ownership report was filed in connection with a sale, then that would be your complete report that would supersede the previous Biennial filed with the Commission.
Some companies have Board changes annually so they end up filing supplemental reports as well. In that case, the last full Biennial and any supplemental reports should be in the file until the one that's due pretty much right now goes in, then the old one(s) are eligible to be removed.
I'm not an attorney, so these are my commonsense interpretations of the rules as I understand them, and I believe they match up to the information in the good 'ol' Self-Inspection Checklist.