Keep them locked, if you read the walk through, you will know when the scene should begin. For example if you want the Xianne Scene unlock her at the Meeting Koko scene, when the scene with Xianne begins, simply lock her again, the story will act as though you did not go through the Xianne scene. If you want the Aunt Amy Scene, unlock her at the MC and Mel at Hank Sharps office. Once you get to Aunt Amy at lunch and you click make things work, and you progress a few lines, lock Amy again, and finish her scene any way you want.