-Whenever a Sim dies, you can keep them alive by using the move_objects on code to delete the Grim Reaper. Save and exit the game, then evict your family. You will have to refurnish your house, but at least your Sim will still be alive.
-If your Sim is dying, enter build or buy mode, enable the move_objects on code, and delete the Grim Reaper. Then, delete the dead Sim. When you return to live mode, click on that person's picture and they will reappear with their last saved stats. Note: The "death" music will still play.
-After your Sim has burned to death, the Grim Reaper will appear. Get the closest person to plead with him. They will play Rock, Paper, Scissors, Shoot. If you win, the dead person becomes a zombie. Enable the move_objects on code, then go into the build or buy mode and click on the zombie. Delete him or her, then return to live mode and click on the picture of the Sim that was a zombie. After that, click in the house and they will be revived. Note: This will only work if person has burned to death.