Numbers: key combination (or script) to move items in a pop-up menu

Here is the best way I have found to deal with pop up menus:

Creating a pop up menu from a column of data:

1. Create a column of items for the pop up menu
2. Select all of them. If a blank cell is included, the pop up menu will naturally be "start with blank".
3. Format as pop up menu.  All of the cells will be pop up menus that include all the items in the order they appear in the table
4. Select one of them (probably the blank or first one)
5. Copy
6. Paste it to where it is needed

How to edit the pop up menu and update all of the pop up menus used/present in another table (assuming they are in a column of the other table):

1. In the table for creating the pop up, select the column of items  
2. Format as text or as whatever format of the items should be
3. Edit the items (add new items, delete items, sort, etc.)
4. Select them and format as pop up
5. Copy the popup that matches the uppermost one in the other table.
6. Paste the new pop up over the old one.
7. In this other table, select that cell and the rest of the column of pop ups.
8. In the cell tab of the format sidebar, choose to merge menu items. All cells will get all the new items and they will be in the same sort order as the newly created pop up. If a cell was set to an item that was deleted for the new pop up, it will go to the bottom of the pop up menu for that cell. That pop up will be different from the others.

When written out it is a lot of steps but it isn't all that difficult to do unless you use the pop up in random cells (not a contiguous column or row of cells) or in a lot of different tables.

I don't know how much of that is directly scriptable, except by GUI scripting.