Making 2D Property Lines Follow Topography in Revit and Instantiating Hosted Family on It

Hi I’ve watched MARCELLO SGAMBELLURI video on making properties lines that follow topography [Link]. The tutorial is great, author explained it very well. However, I’m struggling on instantiating hosted families on top of topography. In my case, the hosted families got instantiated below the topography.

Here’s my dynamo code.

Here's is the output of code in Revit 2017.

See the non-hosted family got instantiated below the topography. I'm wondering is there any way to instantiate the hosted family on top of topography. I am newbiew to dynamo, would appreciate if someone explain how do I instantiate the hosted families on top of topography. Thank you.

This can be achieved using the dynamic model updater functionality. Here is a discussion of using an updater in conjunction with the Idling event including two short videos showing examples making use of it.