Making Multi-Sourcing work will eat up lot of band width of the companies that are choosing that route. Given the trend as reported by Gartner, multi-sourcing is the name the game.
Making multi-sourcing work
Step 1: Granularize work
Step 2: Look at the work elements and their interdependencies - How - Using the Design or Dependency Structure Matrix (DSM)
Step 3: Use a Value Model to understand and quantify the value of each player in the multi-sourcing scenario
Step 4: Use a Multi-criteria decision making technique (Analytic Hierarchy Process - AHP) comes to mind
Step 5: Using Lean Concepts of Value, Value stream, flow and pull to make work happen
This is a tough ask - to put is mildly! Are the players ready!