I don't know how to move a post from one topic to another (already existing) topic.

Here is scenario I encountered:

As it often happens to long threads, it took a new direction, and then some of people responded to original topic while others commented on the new one.

So I took the first topic from the thread which deviated, and “moved” it to another topic (actually creating a new topic for it).

However, there were 2 responses to that “deviation” which I wanted to move to that same (newly created topic). But the interface of “move-operation” didn't allow me to do this.

Or I didn't understand how to do it

The workaround I did for those 2 messages:

1) I copied their content.

2) Posted them as replies (from me) to the newly created topic

3) Re-assigned the authorship of these posts from me to their real authors

4) Deleted the original posts

It has two drawbacks – 1) the process is long 2) the time-stamp is changed 

Is there the way to do what I wanted better?