In Sims 3, you could queue up the plan outfits action on a sim, and swap to a different sim. When first sim got to the plan outfits action, it would automatically swap back to that sim so you could plan their wardrobe.
I have noticed in Sims 4, that if I queue up that action, then swap to another sim, that when the plan outfit action is reached, it goes into CAS for whatever is the active sim. I am not sure if this is meant to happen, or if it's a bug. It happens consistently, as I will queue it up for a sim, then swap to another sim to queue up stuff for them.