Why is this only coming up now, because the story previously was that she had picked up a lost soul human spirit who was pestering her and hard to get rid of?

We were not perpetrating a falsehood simply to deflect having to bring out the darker underlying truth of things. There was, truly, a lost soul human spirit tormenting her. It was facilitated and arranged to happen by an extraterrestrial spirit who monitors her from time to time and looks for ways to cause her trouble. So that possession happened because she was softened up by the extraterrestrial spirit who also directed this particular tormentor to her specifically, knowing that it would be an unpleasant liability. We were not asked specifically about extraterrestrial involvement and so could not describe that extra component at that time.