I am working on a python app and I am trying to logistically plan how saving/loading files will work

In this app multiple data sheets will be loaded and they will all be used in some capacity, the problem I am having is that I want users to be able to save the changes to the files that they have imported.

I was thinking more of a save file that holds the content of all the files they have loaded into the app. But I have no idea how to structure this! I've done some research and heard that parquet/feather are good formats for saving files but I don't know if they support saving multiple data frames to the same file.

The most important part about this is that the files need to be loadable by pandas/another library so that a user can save the changes they've made and then load it back up later if they were so inclined

Any advice is appreciated!