Item validation org for Purchasing multi-operating unit scenario

We have 2 operating unit under the business group:

• Operating Unit - US = US DIST OP UNIT
  • Inv Org = SMD
  • Item Master Org/Item Validation Org = IMO
• Operating Unit - Canada = CA DIST OP UNIT
  • Inv Org = S20
  • Item Master Org/Item Validation Org = IMO

For CA DIST OP UNIT, we have defined the item master org/item validation org as IMO (under OM > System Parameters)

While setting up Purchasing for Canada, we're unable to see the IMO as the inventory org under financial options (Purchasing > Setup > Org > Financial Options > Supplier-Purchasing). We only see the orgs defined under CA DIST OP UNIT.