Do mods get applied over multiple computers when I link my Nexus account to my Steam account?

I am one of three people using a Steam account and I am not the original owner of that account. We all have Skyrim Special Edition and I want to use a mod in my game, but I do not want the mod to get into their games, or be linked to the Steam account, in case the mod has malware or breaks the game.

When I click mods in the game menu, it says I have to log into my Nexus account and I do have one. But it says the Nexus account will be linked with the Steam account. If I log into my Nexus account, will my mod activity be visible through the email account tied to that Steam account or on the Steam account itself?

I worry that if that Steam account is linked to by the Nexus account and I get malware from a mod then it might infect that Steam account. I also don't want any of my mods to get into the games that the other two people are playing because I know that mods are sometimes unstable and I do not want it to ruin the game for them. I just want to keep the mods I use on my computer only and use them in my game only and not have the mods affect the Steam account at all because of the risk of getting malware but I'm not sure that's possible because I'm using that Steam account to play the game in the first place.

By the way I am using the Vortex Mod Manager, if that's important, and I haven't started using any mods in the game yet and I am planning to use a race mod and combat enhancement mods.
Please give me very detailed answers to all my questions because I am confused about what to do about those things.

Solution 1:

• I'm not sure if you're referring to Family Library Sharing, or if all three of you are actually using the same account. In case of the second: this is actually not allowed as per the Steam Subsciber Agreement:

  "You may not reveal, share or otherwise allow others to use your password or Account except as otherwise specifically authorized by Valve."

• If you are using Family Library Sharing, and all three of you are on different computer systems, there is no problem at all, and you can mod to your heart's desire, as the mods you install, or tweaks you make to the settings and .ini files, are completely local, and won't change anything for the other players.

• If by a Nexus account you are referring to an account on nexusmods.com, you can just link it to your own Steam account. It's just for registration, and to be able to download mods. It is not tied to the games in your Steam library.
  Log in to your personal Steam account (if necessary, create one), log in to Nexus, and connect those two. Now you can just log out of your own and in to your friend's Steam account.

• As always when this matter is brought up, I suggest using Mod Organizer 2. It is way more flexible, customizable, and therefor a lot more stable. You can even make different profiles with different mod setups, for easy comparison and error checking.
  The last feature is important when using the same computer system (and the same game, if from a single platform, like Steam), as it will allow you to share your local mod database, but customize what is activated for each player.
  What's more, as long as you don't interfere with the files in the main game folder (where SkyrimSE.exe and SkyrimSELauncher.exe can be found), users not wanting to use any mods, can usually just start the game through Steam and won't have to deal with anything else.

• Last but not least: I have never had any problems with malware from downloading from the Nexus.
  As always, though, with other, less reputable websites, be more cautious.