Joe,
Going back to 17/May:
Only problem is, it's difficult to reorder threads once things have been posted - so it would be hard to have added songs in alphabetical order.
I get away with it in the BBC song book threads by opening two tabs with Mudcat, and pasting from one to the other (usually between two 'edit' boxes to retain any format).
Admittedly this loses the name/date of the original post, and the originals don't appear on lists of posted comments. The original name/date could be retained by starting each post with a copy/paste "This post was originally made by Joe Bloggs on 32nd July 2020". Obviously it still won't appear in 'joe bloggs's' list of posts, but it is identifiable. (and not so much problem if posters know in advance, like the DTStudy threads, that the discussion is open to editing actions)

Also, if I know I'm going to be shifting a good number of entries I go through first creating a sufficient number of new posts "This post deliberately blank . . ." so no-one can post something in the middle of my transfer actions.

If it involves a large number of posts you may need one or more volunteers with edit buttons. (Oops, just used the 'v' word.)

Hope this helps. I haven't sent it as a PM as others may have better solutions.

Cheers