Hello Flakbait
If you goto the aheditor/terrain
folder you will see a file called shpfilter.txt, open this with notepad.
This list of items are those that won't show up in the editor shape listing when editing a terrain.
If you remove an item from that shpfilter.txt list it then will show up.
If you add an item, that item will then not show up in the editor mode.
Try starting a new terrain to check this out.
Secondly how about going to the editor/terrain/groups and rename one of the group items you want to rearrange
(eg AFDbl-1.obg). Rename it something else (eg. Flak-AF.obg).
NOTE! make backup of the original!
You then can open this with note pad and remove the items that you dont want then save the changes.
Then while in the editor in you terrain select your new group, add to it, and then save it.
Pokie