Brooks Stevens and wife Alice did have three sons (Kipp, William and David), and a daughter Sandra . . . but I'm not sure if the son was the "re-designer" on this car or not. Kipp is currently the President of Brooks Stevens Design Associates in Milwaukee, so I guess it's possible if the time frame adds up - not sure how old Kipp would have been in 1958 when the "Saci" was first being designed.
Interesting also about the name "Saci" . . . certainly wasn't aware of that.