hi, so i bought Arma 2 combined operations (DVD) not long ago. i installed it on my pc and it installed it onto my desktop not onto steam. i realized that this was because i didn't buy it through steam. but is there a way, on installation, to get it to install onto steam as if i bought through steam. when i got Skyrim on DVD it installed onto steam but this doesn't happen with Arma 2. any help?