Is it possible to create a mod to overlap CAS costume makeup or does one exist? It'd be handy for combining band-aids and contacts, but seems awfully far fetched.

Twallan's Master Controller has a function that supports this.
It's under "CAS" and it also has some other great tidbits that help make your CAS run somewhat smoother.

Oh? I have Master Controller, and had no idea it could do that, how does that work?

http://nraas.wikispaces.com/MasterC...er-Settings-CAS

Just scroll through that to get a general idea but what you're looking for is "Multiple Makeup Per Location" which allows you to place multiple CAS makeup (including Costume makeup).
Hope this helps (somewhat).

P.S - what I was referring to in regards to CAS running smoother is the "Show in Compact Form" interactions. They basically makes it so instead of showing you 3 of each style (say, of a shirt) - it will only show one of each - thus making CAS run a bit faster due to it not being clogged (with the multiple icons) so much when it refreshes everything every time you move categories.

Oohh, thankies :lovestruc
Can't believe I never knew that, and the compact thing would help since I have too much some CC

You're welcome :D.
(Yeah, I never knew about it either until I saw someone posting about it on Tumblr, so don't feel too bad XD).

Oh my gosh, it must have been fate that I clicked on this topic. Thank you MrsNervousSubject for this information. I cannot play without the amazing mod that is Master Controller, so I've used it quite extensively. However, I had no idea such a feature existed and even though I HONESTLY don't have a whole lot of CC + gaming PC, it still borders on unplayable garbage whenever I'm picking outfits.

Oddly enough, it's Adult/Young Adult females that absolutely kills any joy to be had in choosing outfits for them because they have more items than anyone else (at least in my game), resulting in crazy, insane mondo-lag. However, I'm pretty confident this compact form thing will be a big help, so thank you!

Don't thank me, I'm just your friendly neighbourhood Spider-errr, helper.

>.>
Almost gave away my SECRET!SUPERHERO!IDENTITY.

No but seriously, you're very welcome.
There's just so much stuff Twallan's mods do that I don't think I'll ever be able to master it all.