Idk if I get exactly what you are asking but the steam version is completely separate from other versions. If you buy on steam, everything goes through steam, if you buy direct, well its all direct. So if you want a steam version or have it connect to steam, as far as I know, you need to buy it via steam, if you don't, go to the SE store, Amazon, etc.

imo the non steam version is leaps and bounds better to have since its not locked to steam, you do not need to buy everything via steam, if steam suddenly goes down for any reason you still have the game and you don't need to worry about any blips in steams system.