hiring manager field populate based on the primary assignment number in the job requisition.

We are using a template for the job requisition creation, and currently, the hiring manager, recruiter and collaborator fields display all the assignments for the person, not only the primary assignment. I want to populate the field value based on the primary assignment, especially for the hiring manager, so that the approval flow gets assigned based on the primary assignment. Is there any provision to resolve it, such as using a fast formula or setup?