Is there a way to add a user by their steamid to a group? I want to be able to add people that are offline and to avoid admining the wrong person with a similar name.

This command only seems to take names and if I use a steamid, it doesn't work.

oxide.usergroup add <name><group>

Should work with steam IDs completely fine. Worked always for all the shops and etcetera (or how else could they work)

The command works with names or Steam IDs, as mentioned above.

oxide.usergroup add STEAMID GROUPNAME

Hmm ok that's strange, it wasn't working before.