Load Completions for Self-Paced course and adding to Initiative for renewal

Summary:

I 've created Courses (with one offering with one self-paced activity) using web links that auto-enroll users through SSO in an external platform. Each course will have it's own initiative (no audience - new users will be added either by person or person list) with reassignment rules: each course has a due date of 30 days with ongoing due date of 30 days to be reassigned at an interval # of days 30 days before expiration date.

I need to get all employees with past completions into those initiatives so that their next assignment will be created 30 days before their expiration date (in other words so that no one has to retake it when they are added to the initiative unless they expired more than 30 days ago - at least I think that's what I need to do.)