"Anonymous. Are we talking about the same thing here. If I stretch my left side I will sway to my right."
Apparently not! Left stretch does not imply anything about sway.
Let me go back to the couple in the line and make a simpler observation of the same issue: the man's left side is too open, because the lady is more to the left than he is.
Correcting this would have nothing to do with sway, or position of the weight.
"It becomes easy to understand CBMP sway "
What is "CBMP sway" ???
CBMP and sway are different aspects of dance body position. And you can't write any general rule about which direction of sway might work better with CBMP, because that depends on which direction you are moving (sway against movement generally works better than sway into movement)
"Both shoulders will turn an equal amount."
Obviously - but what will they turn relative to, and when?
"If you do a Feather Step and shape to your left you will see the error of your ways as you also try swaying to your right at the same time."
No problem at all. Shape and sway are not the same thing. How many times do I have to repeate that? You can't understand the left stretch I am talking about, because you keep imagining that it is something that it is not.
"There is no left stretch in a normal dance hold."
Yes there is. But you don't understand that, because you keep mistaken the necessary left stretch for other things - most of which would indeed be severe mistakes so you are quite right in not wanting to do them. But they are not the left stretch that is necessary.
"As I have said to stretch my left side will cause a shift to the right."
If it causes you to shift to the right, it is not the proper left stretch. A proper left stretch does not move your body weight. A proper left stretch does not inline your arms. If you attempts at left stretch produce these results, then either leave it out for now or seek in person professional help.