I don't believe! :)

it's a cool discover!

Beware that the requested fillet must have a minimum size (a little smaller than the diameter of the smallest sphere otherwise the operation is refused)!

But it does not work between several separate spheres!

(and it doesn't work with a sphere and a box for example!
(it would be necessary to cut it and remove a bottom of the box and make a Joint command!



In any case cool form with only 2 separated Spheres "Filleted" with the Phiro method and a simple Twist with inclined axis! ;)