Reading from George DeAngelis The Ford Model A as Henry Built It, page 11 says that Eugene J Farkas, a Ford engineer, assisted Henry and Edsel as George documents:
The first step was simple. As various engineers recall, the dimension were immediately decided upon. Ford himself stated:"Edsel and I decided on the wheelbase and the size right away…after that it was a matter of working things out on the drawing board until we got them right.”
Unlike other automobile companies, Ford had not permitted the development of a research department an engineering staff or a styling department – whose skilled personnel could have been working on the advance projects.
As the job of developing the new car was undertaken, Ford delegated various responsibilities to his associates and gave Edsel a free hand in styling the body. (Eugene) Farkas, at first, was given charge of the overall design, but later was reassigned to special projects including brakes and axles. . . Joe Galamb designed and engineered the body and frame under the close direction of Edsel…
Then move onto pages 122 – 125 for a detailed explication of the “Three-Window Sedans” by whatever term you may use, but it is clear that:
Both manufacturers designed the body to the same basic package dimension provided by Ford Motor Company but there were major differences…”
And you can read about them from there.
It is clear in my mind that Edsel had a close relationship with Briggs particularly in the development of the Cabriolet, the Deluxe Roadsters and Phaetons, the 190A and 400A. From that, it might be inferred that Briggs was preferred over Murray because he created a better car?