Ok so the S2 download will allow me to use my S1 license and "some" (demo) content from S2? Full S2 content comes with S2 license purchase... 
What files do I need
I used to have lfs. I just logged in at the website and downloaded S1 since that was the license I had. I would like to try out S2.
What files do I need? Should I install my S1 and log into game, then dl S2?
What files do I need? Should I install my S1 and log into game, then dl S2?
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