Is this what you mean?
I'm just winging it with families. I don't really know what I'm doing. The family is called Blue. When I run the demo, it seems to reference the bottom point of the bottom
member of the family. That is, the near wall. When I walk up to what should be in front of the rear wall nothing changes. I am behind the near wall and behind the rear wall too.
Just in case anyone is in the mood to waste a few minutes, here's the link to my cap file.
Once the cursor is hovered over the file 'zOrderYpositions' a green arrow comes up in the top right hand corner. Left click on that and the option to download comes up.