Can you lock vertices on a form to a parametric sketch?

[bri95HX6]

I'l like to create a form that is "tied" to a parametric sketch.  That is, I'd like to be able to change my sketch and have some of the vertices/edge in the form conform to the new sketch.

Is this possible?  If not, if I have a body that has both parametric and formed parts,  when the parametric parts change must I manually change the form to conform to the new parametric body?  Is there a better way?

[TrippyLighting]

Forms (T-Splines ) are currently not parametric. So if you do snap a T-Spline vertex to a sketch and then modify the sketch you'll have to re-snap the T-Spline to it.