The development of complex systems involves a variety both of methods and tools to generate, store and process development-related data and information. This brings Digital Continuity as a key topic for current research. This paper presents a Model-Based Systems Engineering (MBSE) approach that contributes to achieving Digital Continuity from the early phases of the product development process. This approach has the system architectural specifications at its core, which contains an executable system behaviour model. To provide early verification and validation capabilities, the specification model is enabled with real-time physics simulations and utilizes virtual reality and augmented reality technologies. Furthermore, the same specification model is used to control and communicate with the physical system, collecting real-time data about its operational state, resulting in a Digital Twin while minimizing additional development effort normally necessary for a Digital Twin. The approach is applied to the complete development life cycle of a medical delivery drone.