Suppliers and Sub-Suppliers
Direct Suppliers and Indirect (sub-contracted) suppliers. The supplier management process needs to maintain an overseeing element regarding direct suppliers that may then sub-contract other suppliers for whole or part of the services being delivered.
In many cases the service provider wants to have too much control and interferes with the direct supplier relationships. It is a fine balance to get right, but only through clear expectations, development of trust and openness can the service provider gain the assurance.
ISO 20000 defines this supplier-sub-supplier relationship and provided there is a some control measures in place the actual degree of those control measures and the nature of those control measures is recognized as being dependant on the situation.