Virtual Commissioning (VC) is an increasingly integral practice in the engineering of production systems, evidenced by growing research and industrial adoption. Advancements in VC model fidelity, computational performance, and automated generation are improving the validation of complex production systems and point toward further applicability beyond conventional control software validation. In industrial practice, however, VC models are still confined to their original use. While emerging applications for VC models in the operational phase highlight the potential for model reuse, a structured method for transforming these valuable engineering assets into Digital Twins (DTs) is still absent. This paper addresses this gap through three main contributions: first, by clarifying the VC/DT boundary within production contexts and identifying open research questions; second, by introducing a novel six-phase transformation method; and third, by identifying industrially-derived use cases and their specific requirements. The proposed method adopts the Design Science Research (DSR) methodology to systematically structure the problem space, derive actionable objectives, and design the iterative development process. Initial results include a set of industrial use cases with their corresponding requirements, as well as the exemplary execution of one development cycle. Finally supplemented by a qualitative cost-benefit analysis, this work offers practical guidance for realizing VC-based DTs that support operational tasks in production environments.