I'm adding this post to report as something to include in the OP.
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Instructions to continue game into Season 2 (PC/Mac):
1) Make sure you have installed -- in a new folder -- an unmodified version of the latest version of Season 1 (CompanionofDarkness-Season1-Chapter9)
2) Load your last (or second-to-last) save from any previous version of Chapter 9, then play through to the end until you see a message saying file saved (just before credits). You don't need to make a new manual save.
3) Install -- in a new folder -- an unmodified version of the new Season 2 game (CompanionofDarkness-Season2-Chapter10)
4) START a new game -- don't load any old saves -- The game should start with a recap of some of your in-game choices. Once you get through that and the story continues, you should make a new save.
5) OPTIONAL -- close the game and install any mods you like to use, then start again, load your new save, and enjoy!