Is it possible to set up one-to-many order pairs in a vehicle routing problem?

No, it is not possible to set up one-to-many order pairs in a vehicle routing problem (VRP). Ordered pairs in a VRP are strictly a one-to-one relationship. The problem arises when adding extra records to the Order Pairs table to reflect the different stops, the Network Analyst solver fails with the following messages:

Error:   
Warning: Order Pairs (FirstOrderName = "[Name]" has a SecondOrderName value for an order that is already paired.
Warning: Order Pairs (FirstOrderName = "[Name]", SecondOrderName = "[Name2]") has a SecondOrderName value for an order that is already paired.

As a workaround, create duplicate stops for each extra delivery address in the order pairs Excel table. For example, if the situation is to deliver from Store A ten packages to Shop A and another ten packages to Shop B, create a duplicate record in the OrderName1 with a different name but with the same location address.

For more information on vehicle routing problem analysis, refer to the following ArcGIS Web Help page: Vehicle routing problem analysis