merging sets in Augmented

I have a show which has essentially a different set for each act. Act 2 opens out from Act 1 and Act 3 opens out even more is the basic principle. Because of the masking issues, I have been finding it difficult to have all 3 set states in my augmented file. I can and have been managing with using the most opened-out version of the stage but it would obvioly be more accurate if there was a way to have all three states in there to toggle between. My best guess is nesting them is probably the most efficient way, but I don't actually know how to nest to even try it out. If anyone has any idea on this you would be my saviour. 

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