Personas: Moving fields from subscreen to a main screen

I am attempting to use Personas to simplify the VA02 order change transaction.  One of the key requirements is to move many of the fields which are buried in the subscreens (located under Goto/Header) to the main screen.  I know that it's not possible to move the actual field since they are two seperate screens, but I have been trying to recreate the field on the main screen and sync that "fake" field with the real field from the subscreen.   Unfortunately, I've run into a few obstacles and I'm wondering if anyone has had any luck making this work?  The main issues I've encountered are as follows:

1. I have written a script which populates the "fake" field from the subscreen value, but I am unable to figure out a way to then update the original subscreen field when the user updates the fake field.  My preference is to avoid making them click on a button to run the scripts, but I haven't seen a method to automatically run a script based on what the user is doing (i.e., saving, opening, etc).  Also, the users will sometimes need to leave the main screen during editing to go to the item subscreens.  When I do that, the values I previously entered into the "fake" fields are wiped out.  The functionality around new Personas fields seems to depend on the user staying on that screen (I'm assuming leaving the screen effectively clears the memory of values in those fields).
2. I have not found a way to automatically populate the dropdown of a "fake" field on the main screen with the values that exist in the real field on the subscreen.
3. Complex screen elements (grids, long text boxes, etc) can't be recreated onto the main screen...I've long since given up on the hope of finding a way to do that.
4. Grids can not be combined into a single grid...like #3, I've given up on the idea that there might be a way to make this work.

The Personas field functionality seems to work fine for displaying values, but once I start allowing updates to the values in the fake fields, it starts to fall apart.  Perhaps I'm trying to force the tool to do more than it can at this point, but I wanted to ask the question to see if anyone has done anything similar with any success.   Thanks!