Re: How does transferring content between stores (Steam, Epic, EA app) work ?

@noob_gembel12  If you mean can you transfer your saves, technically the answer is yes: Sims 4 saves will work with any type of install, and they'll even transfer from Windows to macOS or vice versa.  However, you can't transfer the DLC you've bought in Steam to Epic.  Anything you've bought through Steam will need to be installed through Steam.  So if you own expansions there, and you install through Epic, you won't have access to those expansions, and then your saves might not work properly or might not even open.

@fxxkgravity7  I've merged your post with the master thread for these questions.  No, you can't transfer your Steam-owned content to the EA App.  Anything you've bought through Steam will only work with a Steam-installed base game.

Additionally, you can't directly buy your Steam-owned packs again in the EA App.  You could unlink your Steam and EA accounts, then clear the App's cache and buy the packs again; or you could buy the packs from an authorized third-party seller and register the packs within the EA App.  Neither is guaranteed to work though: the EA App sometimes still blocks people from rebuying their content, and a third-party code might not ovverride the Steam content.

However, it looks from other players' posts (including the one immediately below yours) that you can in fact get your Epic-owned packs to show up in the EA App.  You may need to uninstall the Steam version, install from Epic, and launch the game once from Epic before the Epic-owned packs will show up in the EA App.  But once that happens, you can uninstall the Epic version, install the Steam version again, and download the Epic-owned packs through the EA App.  I think.  I haven't tested this myself; I'm only going from other reports.

yes, your sims are saved in your savefile on the computer. so long you make a backup.