How do we create multiple Organization Units in single Organization in Oracle Field Service ?

Hello,

We've created 3 Organizations in OFS, and are trying to create multiple Organizational Units under them. But, system is allowing us to create an Organizational Unit inside an already existing Organizational Unit under a different Organization. We're unable to create an Organizational Unit independently under a particular organization. The field Org Unit/ Bucket has become mandatory to select while creating an Organizational unit. Where do we edit this ?

Does anyone have idea why is system behaving this way ? Or is there a restriction like - There has to be only one organization against a project & an organizational unit under it. Remaining Org units must be created under this Primary Org unit ?