AP Invoice Approval Per Department

Hello,

Our client has different operating units (OUs). One of these operating units contains four departments, each with its own Invoice approval hierarchy. I want to define these departments in the Invoice Descriptive Flexfield (DFF) header. However, the challenge is that the DFF is only applicable to one OU. Is it possible to define a DFF and make it specific to an OU? Alternatively, is there a better way to address the approval requirement?

Please note that the Version EBS 12.2.12

Thank you