Any way to test older CC?

You could just add it one by one and see if it shows up in CAS and on Sims, but you could also update it in Sims 4 Studio.

If you are able to play your game and everything looks fine. You don't need to update anything. Broken CAS CC will most likely look funky. Sometimes it will crash your game, then you will have to use the 50/50 method to find the culprit.

These are the current updates available for CAS CC in Sims 4 Studio:
Repair missing mesh for men's underwear/swimsuit
Fix glassy looking Maxis Match hair that broke with Cats and Dogs Patch
Update CAS CC Pets patch fixes a problem where Sims clothes were morphing oddly in CAS
Fix clothing that appears in the shower

If you have one of those problems, download Sims 4 Studio (membership is required but free). At the top of the main page click on Content Management, then batch fixes. There are options for CAS and Objects. If you use a batch fix it only applies to the CC you have in your Mods folder at the time you run the fix. Anything you add in the future would not be covered.

One of the best features of Sims 4 Studio batch fixes is disallowing CC for random townies, aliens, and vampires!

Another feature is that you can look at your CC individually and delete unwanted or broken content directly from the program. Press the My CC button on the main page and a new window will open. The file names will appear in a column on the left and a picture of the CC will appear in the middle. For further information on how to use Sims 4 Studio to add the Hot and Cold Filters for Seasons see this thread here: https://forums.thesims.com/en_US/discussion/942074/guide-how-to-use-sims-4-studio-to-tag-your-cas-cc-for-the-6-19-patch#latest
*note there is a batch fix to add the filters to specific items but, I recommend doing it yourself. For example, the batch fix applies the hot filter to all short dresses and I have some dresses that are definitely for cold weather and it doesn't recognize sweaters.

**50/50 Method: Put half of your mods/cc into the mods folder then start the game and see if the issue is still there. If the issue is not there, then you know that those items work okay with the game. Then you can test the other half of your cc/mods. If the issue is still there with the first half, you will need to keep testing them to see what is causing the problem. Then you will need to test the second half of your cc/mods too

"luthienrising;c-16566366" wrote:
You could just add it one by one and see if it shows up in CAS and on Sims, but you could also update it in Sims 4 Studio.

Oh, I've never actually used Sims 4 studio. Do I just load the CC and it auto updates it or do I just save it with the most current version and it auto-updates?