Phil. Only quoting Len Scrivener from his book. Ballroom Dancing Analyed. Never twist the shoulders out of line with the hips. Alex Moore Care must be taken not not to turn the shoulders independently.
Also from Alex Moore page 16 17. As the right foot moves forward and the body turns to the right many dancers allow the Right Foot to travel in a direction diagonal to the wall. This is wrong. It is only the body that turns away from the Line of Dance.( that needs to be carefully read).
A bit more from Len Scrivener.
Never lower then move, always blend the two, lower and move.
To get back to the twisting of the spine. ( after reading the above). It would be wrong on the second quick of a Feather CBMP to try to get your shoulders on the same line as your feet. This in my humble opinion is where the following step the Reverse Turn goes wrong. Back to Len Scrivener who said. If it is not natural it is wrong. Is there anything there you do not agree with.