By Adam Nagy
If you want to check if a SketchPoint is part of a curve (e.g. the control points of a SketchControlPointSpline) vs just a point standing on it's own, then you can do that using the SketchPoint's AttachedEntities property.
As always, the easiest way to find out about this is if you investigate the object in the VBA Watches window:
http://adndevblog.typepad.com/manufacturing/2013/10/discover-object-model.html
If you select the control point in the UI:
.. then you'll get this in the Watches window:
