Sim Creation

1691e80d8c4ca9d2​  Do you mean that the Exchange has multiple pictures, or that there's one picture and it consists of multiple images in collage form?  I've only ever uploaded one sim, one I'd saved and exported as a household, and that upload had one picture, but maybe a sim template exported from CAS has more.

Perhaps collage?

1691e80d8c4ca9d2​  What I meant was, is this the kind of thing you're looking for?

https://www.thesims3.com/assetDetail.html?assetId=9491202

Or do you want multiple pictures to scroll through, like this?

https://www.thesims3.com/assetDetail.html?assetId=9667733

For the first one, I used MS Paint to stitch together a bunch of different cropped screenshots from CAS, then used this tool:

https://www.zindasgoldensims.com/

to replace the default image with the one I made.  (I used it for the second upload too, actually.)  It's safe and simple to use; the only caveat is that the images should be square to avoid stretching.

If you're looking to have several images, like the second upload, then all I can think of is that maybe a CAS template sim has more than one.  The one-sim household I created did not.

Thanks for the info, it is the second one that I am thinking of.  

1691e80d8c4ca9d2​  Then as I said, try saving a CAS template and see whether the Sims3Pack has multiple images.  You can use the tool I linked to check.  If it doesn't, then I'm not sure how it's done, but I can ask around.  Or I can move this thread to the Creative Corner section so more people see it.