Pick material for work orders sub-inventory search

Summary:

When running the pick material for work orders how does it determine the sequence in which it search sub-inventories for stock?

Content (please ensure you mask any confidential information):

For customer Nova they have multiple sub-inventories that the pick material program can pick from and the same item required by the WO can be in multiple sub-inventories. The question is how is the order that the sub-inventories are checked for inventory determined, I cannot see anyway of specifying this?

For example they have sub-inventories A&B they both have stock of item 1. They want to be able to specify that the pick material program should pick inventory first from sub-inventory B and if there is not enough available then pick from sub-inventory A