I have a couple of students inappropriately responding to my discussion. How do I block just them for posting replies?
As long as the discussions posts are graded discussions you can assign the discussions you can create groups within your course and assign certain discussion to a particular group of students(How do I assign a graded discussion to a course group? ).
Otherwise if you want to just close the discussion entirely for comment from everyone you can do so by following the instructions here: How do I close a discussion for comments in a course?
Hope one of these help you with the issue you're having.
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