Create NIR with Specific 'Assigned To' and 'Requested By' Fields

Content

We are creating NIRs along with Items using ' Schedule Product Upload' Job. This job has been scheduled from common user called 'system'. Job is creating the Items based on the UCM manifest file and creating the NIRs as well in Definition status. But the NIRs are creating with header level fields ' Assigned To' = System and ' Requested By' = System. 

This is causing the confusion of who created the NIRs and who is the owner of this NIR.

Is there way to create/update the NIRs with Specific 'Assigned To' and 'Requested By' Fields?

1. I know there is REST API in 19B to create/update NIRs, But using this REST API, we can update NIRs only if it is in Draft or Open status and we can not update the NIRs if it is in Definition Status.