I recently downloaded The Sims 3 from Steam and I have expansion packs such as "The Sims 3 Pets", even though I downloaded the base game from Steam can I still download The Sims 3 Pets expansion pack disc and it will work for the base game? Sorry if this question is confusing, all help appreciated!
This post https://gaming.stackexchange.com/a/55084/169790 says you can get your Steam version into EA Origins.
I recall registering physical Sims 3 disks on an Origin account, then getting digital access to them into the future.
Using this method, if you get all your Sims 3 games/expansions registered with EA, you'll be able to download digital versions of each of them and install.