How to get Origin to recognize a game installed on disk

Okay, so this is a bit complicated (for me). So.... before I got an account on Origin, I download some (a lot) of expansion packs for The Sims 3. I installed them all on disk, and only afew are recognized by Origin. I can still play the expansion packs, but when I look at the information about the ones I've downloaded, some aren't showing up. This isn't a big problem, but it annoys me. Thanks.