In order to move her body, we need to first go to the map where the body that now contains the soul.
For example, if you’re using Hillford’s body as Wendy’s body in Asylum, there’s a Soul Orb in the secret room where Hillford’s body was on your next visit.
You can pick it up, then leave the map, find and go to the map that has the other body you want to put in, catch the ghost, interact with another body to put it in.
If you accidentally picked up the Soul Orb and you don’t want to change your body, you can interact with the body that’s fallen in the truck and put it back in.