How to control "z-level?" of KML overlays

I'm fresh to Cesium after moving away from Google Earth and I'm trying to adapt my KMLs to work properly.

I have a kml with many Placemarks (which indicate the position of ships):

When I load another kml (meant to act as an blue overlay to hide the satellite imagery) it loads it on top of the ships, rendering them barely visible through the partial opacity:

Is there a way to control this KML's "z-level" so that the ships are position above it?

While there’s no z-level support yet, this particular issue should be fixed (or greatly diminished) when #2172 is implemented, which is currently in development and will be part of 1.9 on May 1st (and may even make it into 1.8 on April 1st, but I’m not sure).

Hi Mathew
I am using Cesium with TerraExplorer for Web and am experiencing the same issue with the Terrain sitting above the Cesium kmlDataSource. Is there a way around this zorder issue?