Good question. At first thought, you'd think that alters would know what the other is doing or has done. But that was disproven when Viki went through integration in the '90s. I say this because Tess knew Todd's plans and going to the doctor's office instead of the nursury to grab Starr's baby is the obvious answer. But alters don't know each other's memories, so I guess it's one of the things that the writers forgot to pay attention to.
