a variable radius or chamfer?

 From:  Shaun (MOISHAUN)
4607.8 
Tried this on a few models. The problem is after I difference away the sweep the curves left on the shapes I need are broken into pieces. Is there a way to Join them and still have them be part of the surface? When I do a normal Join it makes a brand new curve that won't work for the Blend.

thanks