I looked, and the way these additional lots are listed is just too inconsistent to cross-reference with the missing parcels (might be possible, but more work than I want to do).
Not gonna let myself off that easy... working on parsing the data in the additional lots field now, it's only 20 characters long. They actually have detailed rules for entering the lots in the user manual, but they haven't been followed very consistently (my favorite is the one that says "YO BUCK LANDSCAPING"). But there are 132,000 parcels with additional lots, so let's see how many I can match up.