V8i SS2 - Interchange infield modeling

I am working on a new 4-lane roadway with a diamond interchange. I am working on cleaning up the infield areas.  What I want to do is have a constant sized roadside ditch off of the ramp alignment, and then have the fill slope from the mainline find the edge of that ditch.  I put the ditch in my ramp template and tried to use a point control to adjust the fill end condition to find the edge of the ditch, but I can't find the ramp corridors in the point controls.  Am I doing this right?

Thanks,
Joe