One could use the existing curve data to extrapolate the additional curves to completely define the surface. I would first set the perimeter boundary curves, check the slope continuity of the input curves, then build a set of patch surfaces linking slope continuity to adjacent patches. This is tough to describe the techniques with words.
Digitizing is just a way to begin the full surface definition.
Google / Look up "Bezier surface" "aircraft lofting"
I don't use Rhino but have another trusted system to do this.
Some think that there are totally automatic ways of creating this data, there are tools and techniques which must be learned.
Rent someone with a digitizer much cheaper
Been doing this too long