Tutorial - splitting surfaces using Split line in SolidWorks?
Here is the Tutorial.
Open the Attached file in SolidWorks or generated a similar surface.
Make the sketch using Spline. Be sure that the sketch is larger than surface.
Exit the sketch. Now under features tab choose curves>>split line.
Select the sketch and curve to project the split line.
Click OK and we can see that the surface was splitted into two parts.