I want to create a spline on a surface via api commands.

I got an array with points on the surface and i'am able to select the surface. I use the command:

swSpline = swModel.SketchManager.CreateSpline2(Points, True)

This method does not work with ISketchManager::AddToDB, so the spline or spline points does not have any relations. I'm able to add coincident relations between the spline points and the surface, but I don't know how to add the 'on surface' relation to the spline and surface.

(I use SW2009 or 2010)

Can anyone help me with this?