In short, we have a separate internal system for tracking student's submissions, since we do programming assignments. Students are required to submit their work through our system and not through Canvas. However, we do have the actual grades posted within Canvas in the analogous assignment instance.
I would like to be able to upload a copy of a student's code to the appropriate assignment to provide more context for graders in SpeedGrader.
However, I am not sure if TAs or Instructors can make Submissions *on behalf of* a student.