SOLVED -Multiple Text Window GUIs

[Baron]

Hey,
   [typical disclosure] I feel dumb for not being able to figure this out, but I've spent a couple hours searching the manual and forum now so I'm swallowing my pride and posting for help now. [/typical disclosure]

    I've created multiple Text Window GUIs which I would like to use for Display at various points in my game.  Except that I can't figure out for the life of me how to implement them except for the General Settings prompt where I can change the Custom Text Window GUI to anything I want, but only as a one-off thing (so I can't use the other ones).  So my question(s):

1. What is the script command for calling different Text Window GUIs during the game?

2. Barring a satisfactory answer to 1, is there a way to change the "official" Custom Text Window GUI with script during the game?  I notice in very old threads something called game.Speech_text_gui = GUINAME which is so old it doesn't even appear as obsolete in the manual.  Surely this is still possible?

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EDIT: SetTextWindowGUI -the missing piece of the puzzle!