Inventory grouping behavior as reference organization for Large volume and minimize item association

Summary:

We have business requirement to implement 6000+ stores and wanted to reduce item associations behavior for PIM Scalability and Performance we have explored Inventory Grouping Behavior to reference organization but not getting expected results

Following clarification will be highly appreciated

We have Setup Inventory Organization Grouping Behavior to Reference Organization while doing Item assignment in Product information management we are observing definition organization attributes are not reflecting in child organization which is defined as reference organization and unable to perform Inventory Transactions

1. Is any ESS job need to Run after defining Inventory org behavior to reference organization ?
2. Does it necessary to associate Reference org in PIM for item association for Inventory Transactions ? If Yes what is the significance to setup item behavior to reference org