Can I only use radius as the shape variable for a circular or sphere in Opt problem??

[hntter]

I would like to use mach-aero to run a test case to optimize radius for a circle or a sphere. The only demand is that object still remains circle (or sphere ) after deformation. If the case is a sphere, can I just build a 8 points FFD box and only move one point to control radius variation? I notice there is an addCircularityconstraints() function in DVCon.py to control the section as circularity, but the radius is needed, which means, as I understand so far, to contraint the radius to a constant value. If my understanding was right, the addCircularityconstraints() function fix the radius that cannot vary with optimization anymore and thus the optimization for the radius will be fail.
Can I make the argument radius in addCircularityconstraints() as a shape variable? Or Is there anyother way to only control the radius of a sphere as a shape variable?

Best wishes