This paper aims to demonstrate the malleability and feasibility of methods on products relevant to the home medical treatment and the design of product and service systems based on the refinement of the theories of framework innovation, and to analyze the behavior relevancy and situation interaction of different subjects. Based on the theory of framework innovation, this paper uses the methods of literature research, empirical research and user interviews (e.g., creating personas and user flow charts) to further demonstrate and refine the "dual narrative line" design thinking, and to apply it to the "reduced trauma" injection system design for children with T1DM based on the development needs of "home medical treatment". Combining the framework innovation theory with the design of home medical products and optimizing the three-layer problem analysis path of relationship description, process description, and vision statement in the "dual narrative line" can not only help to clarify the demand changes and service relationships of multi-users in multiple situations, but also effectively promote products upgrade and service for complex situations.