They're not being replaced in CAS. What happens is that I'll make the outfits, close CAS using the check mark, the sim will; be wearing one of the new outfits and everything will be okay for a while. Later I'll see the sim wearing a different outfit that I did not create. It does not seem to be related to any situational outfit or any of the normal reasons for an outfit change (like weather or getting out of the shower). I've seen it happen and the sim's outfit just abruptly changes without the usual outfit-change animation. There does not seem to be any reason why the sim would be changing outfit at that time. They change into a randomly-generated outfit and not one of the career or situational outfits. When I give them another makeover and get into CAS again, I'll see that the new outfit has replaced one of their everyday outfits.
Makeover puts you into a limited version of CAS where you can change the other sim's clothes, hair and makeup. You can make up to five outfits of each type (everyday, formal, workout, etc.) Yes, it's like having gone into CAS with a playable sim and changing their outfits. I would make five everyday outfits for the sim, including the primary, and often one other outfit of each type. Since the sim was my roommate, I could see what they were doing all day and sometimes they would change into a new outfit that was not one of the ones I created. I would go back into CAS, using another makeover interaction, and see that one of the everyday outfits I had created had been replaced by something else. I've seen it happen, and it does not seem to correspond by anything that would cause them to change into a situational outfit. The outfit that replaced the one I created does not look like a situational one.
I've done this before and it seemed to work fine, although then I was only changing one outfit of each kind. Now I'm giving them five new everyday outfits. I've noticed it doesn't seem to affect the primary, so I'm experimenting to see if I still have the problem after deleting all the outfits except the first.
I did not use cheats to do this, I used the offer makeover social which is available to sims in the stylist career.
Also, the outfits were not any of those I created using the "Create trend" ability which is also part of the stylist career. "Create trend" lets you design outfits that will be randomly worn by sims in world. This works something like situational outfits, except that it's not linked to any situation. For example, a sim walking by outside might be wearing their normal outfit or one of the "Trend" ones.
