This white paper discusses the integral role of the Customer Organisation in the Service Integration and Management (SIAM) model, emphasizing its importance for achieving successful outcomes in a multi-supplier environment. It builds upon Kinetic IT's previous work, particularly the MAIDE model, which outlines key functions for effective service integration. The paper highlights that the Customer Organisation is accountable for the delivery of services and must actively participate in the design, implementation, and operation of the SIAM model. It details the responsibilities of the Customer Organisation, including governance, direction, and business relationship management, which are crucial for fostering collaboration and continuous improvement. The document also addresses the challenges faced by Customer Organisations in balancing their involvement in day-to-day operations with the need to maintain effective oversight. By providing practical advice and insights, the white paper aims to guide organisations in establishing their role within a successful SIAM framework.