My dad knows I love the Sims 3 and got me a used copy of the Pets expansion (PC) when he saw it at a thrift store. My problem is that I have the game, as well as the Late Night, Adventures, and Generations expansions on Steam. Now I know that the steam version and physical copies don't mix, but I was wondering if there is a way to rip the files from the disk and install it manually, like you would a mod! If so, I'd like to know where all the files and such go, so I can make use of my gift. I wouldn't imagine it would be too hard to do this, at least for a modding community!

Not in any way that's legal. Your Steam purchases entitle you to uninstall, register the games, and download/ install them from Origin instead if you want. To that mix, you could add a registered copy of Pets.

But used copies games likely were already registered by their previous ownder. It sounds like that gift isn't really going to be usable for you as you would still need to purchase an unregistered copy of Pets to add.

I have several used discs and the base game and some other expansions from Origin. I have no problem at all. I don't know about Steam. I had never heard there might be a problem, so I kjust installed what I had and now I have a functioning game. The only issue is that I have to have the University disc in my drive to play (it's apparently my latest expansion). I can still bypass the launcher, though.

I have had no problem with the serial number either.

One cannot mix and match Steam and Origin installs like you can with discs. The OP would have to go all Origin to make this work. And that would require entering the registration codes on the original TS3 site to allow them to be added to their Origin account.

I suppose they could try going all Origin for everything else and just use the Pets disc to install that one EP, to be honest I hadn't thought of that. But the Steam installs still have to be removed from the picture for any kind of mixed installation.

So it's a specifically Steam issue, not a general digital issue?

Right. Steam installs in particular are all or nothing, unlike other forms of digital installation.

Good to know that, thanks!

FWIW, I'm running a used version of Sims3 and the only thing I've been unable to do is is access TheSims3.com since they ask for the registration number and if it doesn't match the email used to originally register you are directed to "tech help". From reading online I know pursuing this further will only raise my blood pressure; Evil Alliance has long stated they want to stem the trade in used games so you cannot register a used copy of their games, they will tell you to buy a new copy, press the issue and they will offer to sell you a new manual which has a new registration number ...for $20 (I propose everyone at EA who ever purchases anything used - a car, a book, a pair of jeans - has to pay the difference between their purchase and a new item to the manufacturer of that item).

I have a combination of used and new EPs and have had no issues installing them, nor was there any problem updating my game to V1.67; I can live without thesims3.com, so a pox on their policies.

to answer your questions, yes you can.. to both of them, but would that be legal or not, I don't know.. you might want to ask admin or moderator about that..