Comment mover challenges
To new users, Comment Mover (CM) often seems to behave erratically. Grafted comments do not appear in their destination threads/topics where users expect. Work to improve usability of the module is underway, but CM’s current behavior is predictable and useful if you understand how it works.
A few key concepts
Given how Drupal forums work, how Flatcomments works and how Comment Mover works, a few concepts are important to understandig how to use these together.
Threading vs. threaded display
In Drupal forums, threading and threaded display are two different things. Threading occurs when comments are posted in reply to other comments. Threaded display occurs when the forum is configured to show replies to comments (children) below their parent comments (usually indented).
It is possible to set the forum display to flat and make all comments appear as though they are replies to the original post even though many of them are not. Threading may be occurring even though no threading is being displayed.
Since Drupal forum topics/threads may be threaded or flat, we will refer to them here as “forum topics” (or just “topics”) and the posts that begin them as “forum topic nodes” (or just “topic nodes”).