User blog comment:Gemini Sunfall/Main Story and Sidequest Translation is Done, Now What?/@comment-46910941-20200917052323/@comment-36674939-20200917161734

Part 2 comes with the entire game except for the CGs used for Part 1s H-scenes. You will automatically skip these scenes if you haven't merged parts.

The "merging" process is really just carrying over the contets of Part 1's Pictures folder into Part 2's. That's literally all there is to it.