Topsoil Spread

I want to spread 6" of topsoil in the grass areas of the project.  How do hold down the cuts and fills so that the finished grades are achieved when the final 6" of topsoil is spread?  I can see that if I actually put the spread phase in the sequence before the cuts & fills were calculated, that would get me to the correct final grade, but if there are slopes that will be flattened by the cut and fill process, this would also result in more topsoil than needed since the 3D area of the site before cuts and fills could be greater than the 3D area after cuts and fills.