Solved
Do sims clothing go over underwear?
Is it assumed that sims do not wear underwear when fully clothed, and underwear is only worn for sleeping? In other words, is underwear simply replaced when pants, dresses or other clothing is put on...
The short answer is yes, undies are replaced when other clothing is used. Sims don't have undies underneath their clothes. You have to change to an outfit category (sleep usually) that is underwear is you want them in their undies.
Hope this helps
