Questions about The Elder Scrolls Online - Greymoor upgrade

[Dj Michael Pro]

Hello friends,

I have some questions before buying a DLC upgrade:

I buyed the game "The Elder Scrolls Online" from Steam store and also made an ESO Account in ESO site (https://www.elderscrollsonline.com) WITHOUT having the game there, just with an email and then I linked the game from Steam with the ESO Account. Everything wokred well and the ESO site is telling me that I'm LINKED and I have purchased the game from Steam. Specifically telling me that I have "The Elder Scrolls Online: Steam Edition" even If I bought the "The Elder Scrolls Online: Elsweyr Digital Collector's Edition"

Now I would like to upgrade to the new chapter coming "The Elder Scrolls Online: Greymoor". The question is, can I buy an "Upgrade KEY code" from a retail shop and activate it through the "Redeem Code" section of ESO's site? Will it work, or it will ask me for the CD-Key of the game first (cause I don't have it as I have bought the game through Steam store) and then the code/cdkey that I will buy from the retail shop?

Even If I'm linked with my account from Steam at ESO's site and it supossed to work fine, I'm asking the above question cause in the "Reedem code" section it is sayin "Please enter your Game Registration Code first, then any Membership Time Code or promotional code below".
Am I obligated to buy upgrades only from Steam from now on? Can I buy it also on ESO site? Can I buy it from any other retail shop with a discount? (which is a convenient way considering these days)

If you can help me with these questions, I would happilly upgrade to the game and keep up playing.

Thank you in advance,
Michael.

[Dj Michael Pro]

I did it! EVERYTHING worked PERFECT for me!

I purchased "The Elder Scrolls Online - Greymoor Digital Collector's Upgrade" from a retail store. They sent me a key code and I redeemed it in ESO's site in "Redeem Code" section that I have my account linked with Steam! (did not asked me for anything else, such as base game code first, etc) Then I upgraded to this DLC version with all the collectors and the pre-order items just fine (it tells you that you activating everything, you can see them on the right side of the site when activating), but in the DLC tab of the game in Steam you can't see that you have also the DLC that you just upgrade. (don't worry everything is in the game collection, check it)

Saying it here to HELP other people that having ESO from Steam and they want to upgrade or buy anything else from ESO's site or another retail site! ;)
Keep playing, have fun!