The reason why the Pattersons have talked themselves into thinking that the end result of Mira's discovery that Mike and Deanna would be her declaring Deanna persona non grata and never speaking to her again instead of the heart-rending weeping that's more true to the character is not just that Deanna is sore at her mother because she had a brain of her own and didn't meekly fall in line with whatever stupid thing her husband said or did; one must also bear in mind that they project their own desire to dominate others onto the blank canvas of cardboard villains.
This is why I think that Elizabeth still has yet to be told that she was a participant in a fraud; as far as I've been able to determine, no one saw fit to share with her the 'joke' they were playing on the Sobinskis and, since she has no personal initiative or curiosity, has yet to figure it out for herself. The reason is, of course, because they don't trust her to keep a secret for very long when there's a chance she can somehow jam it to her ugly brother.
What makes that all the stupider, of course, is because the same nasty impulse that makes me think that Liz will never know why Christmas holidays are extra-special for her older brother has me thinking that Mira and Wilf figured out what was to be hidden from them years ago. Heck, for all the Pattersons know, the Sobinskis knew before they did and simply decided to let the baby have her bottle.