How to Move Individual Posts
Moving one or more posts between threads can be accomplished in two steps using split and merge.
Whilst viewing the thread with the posts to be removed, select "Split Thread" from the Admin Options (Bottom Left).
On the next page, enter a new temporary subject and select the check box(es) of the posts you want to move out of the current thread, and click submit. This will split the thread and take you back to the thread list.
Hover over the newley created thread, and make a note of the thread ID "viewthread.php?tid=29".
Now go to the thread you want to add these post(s) to and select "Merge Thread" from the Admin Options.
On the next page, enter the Thread Id (eg: 29) and click submit. All posts in the temporary thread will now be added to this thread.