I'm hoping to play NWN EE with my child. Apparently this requires me to purchase a second key for multiplayer (this is, imho, absolutely ridiculous and anti-customer when it comes to local LAN play within a family).

My situation here prompts some questions.

I purchased all the game DLCs with my GOG account. Using that account, I have installed the game and all DLCs on two machines. To get a second functioning CD key that lets me play any of the DLCs with my child, what do I need to do here?

- Do I need to repurchase EVERYTHING a second time?

OR

- Will the purchase of a second copy of the MAIN GAME ONLY give me a second multiplayer CD key that will work with the installation I have on the second machine (i.e., including all DLCs)?

In answer to my own post, you can simply by the base game and use the CD key from that. My kid and I just played a little Infinite Dungeons together to test it out.

It's a bit shitty that LAN requires 2 licenses. I haven't tried it but I take your word for it.
At any rates, if cases like this pop up, usually the base game CD key is usually enough.

P.S. Not sure if you did this, but I would try to contact support about this, at least ask for confirmation of the keys.