I downloaded The Witcher 3 from the GOG website using a friends account but I want to buy and download the DLC's for myself. I've created my own GOG account and I've manually added my Witcher 3 installation using the scan and import function in the GOG client. Will the GOG client be recognizing this as a game that I brought. *edit* (no I don't think so) If I buy the DLC's using my account within GOG client will everything work correctly?

This is two screens from my GOG client.

The first shows the library as empty obviously because I didn't purchase the Witcher 3 but the second shows the Witcher 3 as being in my library. Can someone explain what's going one here? I'm new to GOG.

Also what is the connect now button? I keep getting asked for a code when i click it but I don't have one...

Getting the DLCs probably won't work if you didn't buy the game on the same account, just adding the game via galaxy doesn't add it to your account library.

So I'll need to buy the game with my own account to play the DLCs... If I buy it will I need to uninstall my current installation and then install my brought version?

That's how it usually is the case, exceting the case there is a glitch or an exception from that rule.

You can still try buying them, you'll either get a message that you can't buy it without the main game or you can pursches it in that case there are 2 possibilities:
1.) they don't show up in the Library until you buy the game (if you were abe to buy it because of a bug)
2.) they appear in your library (in case TW3 is an expeption, which might be the cae because it has a disc-version)

the last posibility is the least likely one because the DLCs are listed in the main games tab.

But you won't have to reinstall the main game.

You do not need to install your bought version.

Edit: Didn't see that JinKazaragi already said that.

Tell your friend to buy the dlc for you as a gift