Edit an unanswered response on the copy (content + file)

As an examiner/teacher, I would like to be able to edit the answers to unanswered questions. Specifically

1. modify the content of the answers in a candidate's/student's exam paper if they have not answered or been able to submit their work, I would like to be able to submit it for them after the exam has closed.

2. modify the points awarded for these initially unanswered questions.