Can you change structural points halfway through a story?
Can you repeat the Classes (Situation, Activities, Fixed Attitudes and Manipulations) in your Throughlines? For example, can you change the Main Character Throughline of Activities to a Throughline of Fixed Attitude in the middle of a story?
Short answer: No and No.
Why? Because the entirety of a grand argument story is to explore a single inequity from multiple perspectives within a single context. Switching throughline domains before the inequity has been fully explored alters the context within which meaning is sought. Context creates meaning. Change the context and the meaning is altered. Some works have multiples grand argument stories or a main story and several sub-stories. Those techniques provide the best solution to having your Main Character explore inequities within different contexts.