I already do that, but the result is not what I expected. The knot point is not the same as the control point, so there is no correspondence between the two points. Sometimes, the control points is too far away from the other.
I have already done, the things that @chuck as mentioned. I insert the knot, evaluate ALL control point of the nurbs searching of the point that is nearest of the knot I have inserted (this because I suppose, that the point that is inserted, is near from the knot) and then set the CV as the desired point. But this is not performing and in nurbs with lot of point, this means a lot of time spent searching parameters.
And I have to this operations a lot of time. So I was searching for something that is secure, quickly to do and optimized.