Thanks Danny,

Thats a handy tip that does work while the surface is still planar and before you started manipulating/moving points on the surface. After you've moved a couple of points on the surface around, adding additional control points to the original curves doesn't have any effect on the number of points on the surface.

I'm now finding that once I start molding my surface to shape I sometimes need additional rows of points to refine the shape a bit more. Is there a technique that could be used to add the additional points ?