Using a Surface Template to Seek an Active Terrain for a Variable Depth Bottom Component

Hi All- Looking for some advice from the Template Pro's amongst us.

I am in the conceptual planning stages of a series of Surface Templates that I would like to setup to have the bottom most component extent its Vertical (AKA Depth) to Seek or Target a Terrain, Surface or even a design component. I have ran several test runs and have not had much luck.

In the below image, I am looking to have Point #6 & #7 seek the Active Terrain to make the depth of my "General Embankment" component, variable based on the surface below it that these bottom points are targeting. Any advice on a workflow to accomplish this would be very much appreciated.