Sue's Overtones response

I think that Harriet and Hetty "hear or acknowledged each other when Harriet puts the scarf on Hetty just before Margaret/Maggie comes in the room.  Of course, this is shown in the action and not necessarily in the script when they are speaking directly to each other.  Even when they are speaking to each other, they are not really looking at each other.  Again, this is not reflected in the script, just in the stage directions. It is though Harriet is really speaking to herself and Hetty is just the "name" of her other self, thus the "inner voice." This also holds true for Margaret and Maggie. Hetty seems to be the voice of Harriet's "evil" self or maybe just the voice of her true self which reflects her real feelings.

In the world of Harriet and Margaret, there is a great deal of control  issues.  Harriet and Margaret both wish to put on a air of haughtiness.  They must have complete control, while at the same time, in the world of Hetty and Maggie, they are striving for control of Harriet's and Margaret's world.  When Hetty is screaming to Harriet about telling Margaret  about the automobile, she is trying to break into the world of Harriet.  At the same time,  Maggie tries to grab at the cakes but is unable to break through to Margaret's world to get the cake.  I find it interesting that in  Hetty and Maggie's world, they can talk to each other even though their thoughts and words are unheard by Harriet and Margaret in their world.  For example, when they said that they hate each other, and at the end when  Hetty says, "I love him - I love him," in which Maggie replys, "He's starving - I'm starving."  After their conversation, the lights go down, removing Hetty and Maggie's world and leaving only the world of Harriet and Margaret's.