Found a post when I was scrolling for guide for playthroughs which was to find out if there is a way to duplicate saves.
That post was too old so I made a new one.
Open this path "C:\Users\YOURUSERNAME\AppData\LocalLow\Arvus Games\Starmaker Story" and copy the "save.json". THIS ONE FILE INCLUDES ALL SAVES IN YOUR SAVE SLOTS. I haven't figure out how to split up the saves in different slots cuz Im just a noob.
BTW this method is available for many games and I learned it from importing others' 100% completed game saves, so thank them instead of me--Im just sharing this method.
Pardon me if my broken English made u guys confused. Im Chinese.