Transferring TS3 EP's to another computer

Hi everyone! I have a pretty confusing question that I hope someone can answer. I have the sims 3 base game along with seasons, pets, generations, late night, university, and world adventures. My boyfriend bought a bundle pack on his steam which includes ambitions, supernatural, and showtime. Is there any way to combine our games together so we each have the same expansions? My games are unaffiliated with steam and it seems only some of them are on origin when I log in through his computer. I have tried transferring the expansions through USB but every time I try to install one of the expansions (in the same folder as vanilla ts3) it doesn't recognize that the sims 3 is installed and tells me to install the base game.

Please help!

-Desperate simmer