The new patch, (or expansion) has created a new category of sims called "Stay Over Guests". These guest ask to stay at your place for various reasons, and the stay can be anywhere from one to six days. These sims are uncontrollable when you add them with CAS. They appear in the household as "greyed out" and when selected cannot be controlled. Outside of Control Any Sim, these sims do not appear in the household. They act as household NPC's.