In the development of safety-relevant systems, the integration of safety software into functional software is crucial for reliable and safe operation. This paper presents a novel semi-automated process designed to integrate software safety mechanisms into safety-relevant systems efficiently. Leveraging a model-driven engineering approach, the method initially separates functional and safety source code and then subsequently combines them in a semi-automated weaving step, producing functionally safe source code, ready for compilation. This approach incorporates expert safety engineering knowledge during the setup phase, facilitating the integration process. The proposed methodology not only enhances cost-effectiveness and reduces human error but also supports the quick evaluation of various safety configurations. A proof-of-concept implementation, demonstrated with an adaptive cruise control system, illustrates the practical application and effectiveness of this method. Future work will explore the preservation of timing behavior when retrofitting safety mechanisms, potentially extending the applicability of this approach to further use cases.