Getting a submission_id without doing a manual or automatic assignment of a peer reviwer

[maguire]

I am trying to copy peer review assignments from one assignment to another. Currently I can assign an assessor to a submission (either via specifying the submission_id or the user_id associated with the submission_id). (The programs are available from Assigning a peer reviewer to a submission: Chip sandbox ) However, I seem to be unable to find any submission_ids until I have assigned peer reviewers to an assignment. When is the submission_id assigned? Is there a way to force the submission_ids to be created without doing an manual or automatic assignment of peer reviewers?