The chapter delves into the integration of advanced Industry 4.0 technologies within Sustainable Enterprise Resource Planning (S-ERP) systems, focusing on the critical role of Digital Twin (DT) and Additive Manufacturing (AM) technologies. It explores the transformative impact of these technologies on modern industrial processes by enhancing real-time monitoring, predictive maintenance, and process optimization. The chapter emphasizes the need for a systematic approach to integrating DT and AM within S-ERP systems, highlighting the benefits of combining real-time data analytics with advanced manufacturing capabilities. It outlines a methodical framework for this integration, detailing system architecture design, the implementation of DTs, the optimization of AM processes, and the continuous improvement loop facilitated by S-ERP. The chapter also discusses the challenges of achieving seamless integration and the potential for significant improvements in efficiency, sustainability, and product quality through the synergistic application of DT and AM technologies. This comprehensive approach aligns with the broader goals of Industry 4.0, aiming to create a more responsive, efficient, and sustainable manufacturing environment.