AutoCAD Civil 3D :: Comparison Point On Conditional Subassemblies

I need to create a corridor that has this section. So I'm using this assembly:  

on which I put 3 conditional fill subassemblies on point A, one for fill conditions of more than 2 m that would daylight at 2:1 until it reaches 2 m down and then daylights at 1:3 until it reaches the EG. Then I have another for fill conditions of less than 2 m that only daylights at 2:1 to the EG, and the last one is for all cut conditions.

As expected I have the following problem in some stations that have fill conditions on A of less than 2 m but more than 2 m on B:

Is there any way I can make B the comparison point without having the following problem on cut conditions?

Or that I could create an assembly with the condition that when I have a fill of more than 2 m on point B it daylights, from point B, at 1:3; but when B would be on cut conditions it daylights from A?