Can I copy Battlefield 4 files to Steam Library?

Finally after trying so many times I've got it working.

How I Did It Wrong:

I posted this question here after trying several times and failing and this is how. I initiated the install in steam, it started downloading. A folder was created for BF4 in my steam library like this: D:\SteamLibrary\steamapps\common\Battlefield 4 . Then I exit the steam and copied my installed files in the above folder. And then I reopened the steam and it started downloading the game where it did leave it before exiting, from 10 MBs.

I did the above step a couple of times and failed each time in letting steam recognize my game files, then I thought that steam doesn't actually download the games into their folders directly but it downloads them to a separate folder as this: D:\SteamLibrary\steamapps\downloading, so third time I copied my installed game files in this folder instead and yet it was same result, no recognition of game files by steam.

How It Should Be Done Correctly:

This is how I made it work for me and I'm sure it will work for anyone and any game.

1. Open steam
2. Initiate the download (it will create the folder in steam library as this D:\SteamLibrary\steamapps\common\Battlefield 4
3. Pause the downloading
4. Uninstall the game from steam, yes uninstall, it will remove the files from D:\SteamLibrary\steamapps\downloading and will not delete the folder it created for the game in D:\SteamLibrary\steamapps\common\.
5. Exit the steam
6. Copy your installed game files to the steam library folder.
7. Open steam
8. Initiate the download again
9. This time steam will start discovering the game files instead of downloading.
10. The above step will only take few minutes and you will be all good to go.

as my game was up to date so steam only downloaded a few MBs and that's it. I hope it helps anyone who's reading this.

As you probably know, BF4 is an Origin game either way. You merely bought it on Steam. Launching the game on Steam should bring up the Origin application.

Because Steam doesn't know you have it on Origin, Steam will still force you to re-download it. Fortunately, according to multiple users on this Reddit thread, you can use an Origin download to at least partially skip a Steam download. It worked for Luminoith even though their Origin installation wasn't up-to-date:

Although my Apex Legends game was not up to date on the Origin client, I pretty much did the same thing above.

I started the installation on Steam, let it download about 500mb, and then paused the download and closed Steam. Afterwards, I moved the Origin download into the newly created Steam folder for Apex, and re-opened Steam to continue the download. Initially it said I had 47GB to download and immediately dropped down to 22GB.

Pretty sure this method works, just make sure your game is fully up to date on Origin before trying this method. Verified the files and everything was good to go!

You will find the Steam installation in Steam/steamapps/common.