I am looking to get the Sins expansions, and I am in somewhat of a predicament. I purchased the box edition of Sins, and used impulse (or gamestop whatever it is now) and I do not want to keep using it. So if I purchase the expansions off of the stardock website, will I be able to play the game and expansions together or will I have to buy the base game on the Stardock website as well. 

The same goes for steam, if I buy the expansions on steam but still have the base game on impulse, will it work? 

Thank you for your time.