Hey Jenny-TS3!
I'm not entirely clear what you are asking. The "Create-a-World" tool is quite a bit different from the standard "Sims3" environment, I confess I've not messed with it yet.
Most of the "public buildings" you see in screen captures of the Sims3 (the bookstore, supermarket, etc.) are called "rabbit-holes" by the developers. Your Sim can usually only "enter" the buildings, with limited abilities to interact with the "rabbit-hole" (the playable Sim "disappears into the rabbit-hole" for a certain amount of time to accomplish whatever task, with no direct control by you while they are "inside").
For example, you can click on the "Day Spa" (a building in the world) and select what type or kind of salon packages you'd like your Sim to have ... your Sim enters, disappears from your control for a bit, and then comes out of the building. Or eating dinner at the Bristo or Cafe: your Sim chooses to eat, enters the building, and later re-appears.
So your kleptomaniac Sim couldn't (for example) try and steal stuff while getting a salon package.
The
Ambitions Game Expansion "loosened-up" some of the restriction on the "rabbit-holes" (now there ARE some world building you can enter, for example, the Fire Station or the Consignment Shop) and still have control over them. But I'm not sure if a kleptomaniac Sim could shoplift inside the Consignment Shop (for example). But then you're talking about buying a copy of
Ambitions as well as
The Sims3, so not sure if this applies.
Any Sim you create or play you have the option of saving a "copy" or "clone" to the library. You can use the "copy" to move "between worlds," but once you place a "copy" of your Sim into the library, the relationships with other Sims are broken.
Hope this helps a bit,
-- Happytime