Designate Project Manager as Primary Project Manager in Confirmed Status in-bulk

Summary:

We want to upload Project Managers and designate them as Primary Project Managers in-bulk in our legacy data conversion process, as well as load them in Confirmed status (resource status as confirmed) in our converted projects. If anyone has implemented this successfully, I would like to know which FBDI/REST API was used and the process steps used to achieve this.

Currently if we upload Project Managers using Resource Assignment FBDI, they are created in Confirmed status but not getting designated as primary project manager.
If we try to upload using import project FBDI - Team Member tab, we can get the resource created as primary project manager but the resource status shows planned and not confirmed.