Will importing hand history files over existing db entries..

[MSBK]

So I think it's time to upgrade from PT2 to PT3. If memory serves me right, PT3 DB schema has extra info stored that PT2 did not track. Am I wrong on this?

If not, here is my question/problem:

I seem to have "lost" some of my Fulltilt hand histories. Now I'm assuming you can import your existing PT2 DB (Access) info into PT3. So I'd like to do that to at least have all the sessions I've played and opponent info. Then, if possible, re-import the hand histories I do have to have the PT3 DB contain this data. Will this work? Will it simply re-import the data, overwriting the data and filling in the missing info?

[WhiteRider]

You can't convert an Access database directly - you need to import from hand histories as PT3 reads more information from the hands than PT2 did. You can either import from the original hand histories or export them from PT2. You won't be able to import anything that you don't have the hand history for, but you should be able to get the hand histories from Full Tilt, depending on how old the missing hands are.
Tutorial: Convert PT2 non PostgreSQL database to PT3