in style there is an easy option "curve from surface" which will make a
3d curve anywhere on a surface (including helical surfaces). follow the
taskbar options. you can snap to datum points along the surface with
the shift key.
you can also create a regular datum curve thru points and change the
attribute to quilt/surface. the curve will lie on the surface and go
thru the points (this is a great feature of datum curves) i bet you can
use multiple curves to define the blend sections in both situations.