How can i assign spline at runtime

[lololToday]

see the attachment picture first.

I need to assign spline to curvy controller at runtime.
but there is no such variables. when i access to curvycontroller's instance.

[SerializeField]
private CurvyController controller;

I assigned curvycontroller in the unity editor.
and they worked well. except this problem. 

thanks to read. :-)