Sims 4 on 2 computers
You both can still play Sims 4. However, one computer will need to have the account in offline mode to play Sims 4. While the other computer can be online.
If your sister wants to go online, it may boot your computer offline or just not allow it online access.
The saves are saved to the computer's hard drive. - C:\Users\Username\Documents\Electronic Arts\The Sims 4\saves (By default)
The saves aren't restricted to the specific computer, you can save your Sims 4 folder - [C:\Users\Username\Documents\Electronic Arts\The Sims 4] to a USB key and copy it to your computer back home. So you can have access to your saved games.
Copy the Sims 4 folder from the USB key to the Electronic Arts folder in your documents folder. - [C:\Users\Username\Documents\Electronic Arts]
