I have a problem that I think might be resolvable via a plugin but can not see that one already exists, I am currently using Moodle 2.5.
Our assignment workflow is such that a student submits an assignment, the lecturer grades and attaches a standard feedback document which has a blank space for student comments, student reviews feedback document-adds their own comments-returns to lecturer.
At the moment some lecturers are using multiple attempts with the last attempt being the submission of the feedback. An alternative is to unlock a feedback "assignment" once the main assignment has been graded.
While either of these sort of works neither feels right. Ideally a final stage in Moodle is required for submitting the completed feedback.
Is there a plugin that would add a "Final Feedback" stage where students can upload the feedback file or would this be possible by way of a plugin.
IF i understand correctly I think the best way to actually do with would be with 2 assignment submission as it really is two separate submissions. I would enable completion trackings and conditionally release the 2nd item based on the completion of the first.
As far as I know there is not a plugin for this. I think that mostly the ways you have suggested are used. I personally would check that multiple files could be uploaded and allow 2 files. If the assignments allows for all the assignments to be graded at one time and feedback files returned, I might try adding the multiple file after I had returned the feedback files to the students, to avoid confusion.