Solidworks 2019 has this new feature called Generic Spline, which is something I've been awaiting for a long time. Apparently, the only way to create them in sketches right now is to Offset some other spline, delete the offset relation, and then edit that spline by selecting it. Problem is, in the link above, the pictured spline clearly has 3 control vertices. However, all my Generic Splines have 10 control vertices. That number is displayed in the Generic Spline Property Manager, but it is greyed out, and I cannot change it:

So, my question is, how do I reduce the number of these vertices? I tried the Delete key on them, but it didn't work. Nor do I see any way to increase the number of these vertices either.

Additionally, I see no way to add relations to this spline (except for making it's ends Coincident with something). How is this spline supposed to be worked?