Nurbs Suface Fitting

I am fitting a Nurbs Surface through a set of points in 3D space [x,y,z]. Everything works ok so long as the points conform to a relatively simple curved surface. If the points require a higher order surface than I supply, then obviously the resulting surface fails to pass through all the points.

My question: Is there any way to detect or predict the error between the resulting nurbes surface and the supplied control points ?

No, OpenGL only has a very basic support for rendering splines, any kind of operations on them has to be done by yourself or some other support library.