Used copies of other campaigns

I'm returning to the game after an over two-year absence. I still own the original Guildwars (now Prophecies) and I'm working on getting my fourth character to Level 20.

I'm thinking about buying used copies of Nightfall, Factions and EotN on ebay. Can I do that, and just add the CD keys to my current account? Or will that not work, because the previous owner already added them to their account?

Thanks in advance for the help.

You cant use the cdkey more than 1time otherwise every1 would be doing it i belive but you can get them pritty cheap anyway and besides you wont regret playing them as the games only got better if you ask me

You can not add used keys to your existing account. If you buy a used game you would have to play THAT account. Quite risky if you ask me, since it's against the EULA, you can get perma banned, ripped off, who knows.

Games are pretty cheap now, I suggest you buy a new one and add the key to your existing account.

Since this is really asking about something that's against the EULA.....
/closed.