I have a macro that creates curves through XYZ points on the YZ plane which are converted to sketch entities for a revolve by selecting the curves and using SketchUseEdge2. The curves can take any shape from flat to circular.

This function works well except when the curve is originally defined as a straight lines. Curves defined as straight lines result in line entities which cannot be changed without recreating the sketch where as curves converted to splines are easily editable to and from flat.

Long story short; is there a way to convert a an entity to only spline entities regardless of shape? Can the line segment be converted to a spline after creation without deleting the original line?

My only other option at the moment is to cycle through the curve creation for a flat surface once with some arbitrary radius and then again correcting the surface to flat. Obviously not ideal but simple enough to implement.