The way to implement multiplayer at low cost

https://youtu.be/0QCTCgDsoBY
The above video implements the multi-play of Juno: New Origins by creating a structure between users, sharing a save file, creating a new structure in a shared save file, and sharing and updating the save file with the latest version by using Spreadsheet.

But what if in-game automates the hassle of updating save files every time? When a user participating in multi-play creates his or her structure and presses the Save button, the system automatically updates the newly updated version of the save to other users participating in multi-play. If real-time multi-play is difficult due to conditions, it would be good to implement multi-play by automatically updating multi-play save files.