In order for multi-sourcing to be successful, organisations must be capable of integrating their service providers into a single, cohesive unit.

SIAM/MSI – An introduction to Service Integration and Management/Multi-sourcing Integration for IT Service Management explains:

• the merits of a multi-sourced approach to outsourcing service towers
• the benefits of multi-sourcing contracts with service providers for specified towers
• how to align multi-sourced services
• the challenges of using a multi-sourced model
• how to determine the IT operating model (with reference to the international standards ISO 38500, ISO 38501 and ISO 38502)
• the different types of service integration models (ISI, ESI and ETSI), and the benefits and challenges of each
• aggregating service-level performance
• a multi-sourcing RFP approach, taking into account structural, operational and governance requirements.

If you're thinking of moving from a single-source to a multi-source outsourcing model, SIAM/MSI – An introduction to Service Integration and Management/Multi-sourcing Integration for IT Service Management provides the answers to all of your questions.