Attaching an Object or Mesh or Blueprint to the Landscape

hi. i wanted to attach my objects or in fact in this case my spline blueprint to landscape. let me explain more, i have a spline blueprint, you can see that in the picture, as you can see the ground is flatted or there is not any rise or fall. now i want to create some rise or fall, but when i do that, it won’t effect on my blueprint. is there any option for that or i must create an specific blueprint or i need to do that manually , with changing the angles and moving the spline points?

Rising

Falling

I have same problem/ How can I attach landscape to the bottom of the bluprint?