Please check out the discussion page for less substantiated research and areas to look into.

It is possible, using a combination of mods and EA debug commands, to add Sims to custom worlds using Edit-In-Game in the Create-A-World tool (CAW). Testing to date demonstrates that these Sims will be installed with the world file, and will act just as the premade Sims in Sunset Valley or Twinbrook. However, creators should bear in mind the pool of testers has been small and largely non-technical. These testers have now maintained working worlds across four or five generations without any corruption that is apparent to end users. Suffice to say, worlds populated with this method should carry warnings, but appear to be safe if certain rules are followed. Even so, it is a sensible precaution to back up the world before attempting this. This tutorial assumes readers understand how to install and manage custom content. Players can find the latest version of all the NRaas mods at NRaas Industries Basic Method Preparations #Sims 3 populated custom worlds how to The first thing you want to do is create a fresh folder in My Documents so that you don't clutter up your gameplay library with families you're going to add to CAW. This is an optional step, but it can be very helpful for keeping things organised. Just rename your 'The Sims 3' folder in My Documents, and start your game.

The game will generate a fresh folder and you can have a group of save games specifically for building families, lots, and testing out Beta-quality and below world files. Make sure you install all the appropriate NRaas mods in the new folder that the game has generated. #Sims 3 populated custom worlds install.

Sims 3 custom worlds mods