Carlson Software w/autocad-Grading model vertical faces

Good morning.....Do you guys who make models have an alternate suggestion on creating vertical faces on a model than what I am currently doing? Since I started modeling, I found that creating 2 3DP's staked over each other at different elevations caused issues and the software doesn't seem to recognize one of the 3DP's (Or worse it switches recognizing the vertices in different places). My work around for this has been to offset one of the 3dp's 0.01' (these models are for grading so they don't really care the cut face isn't perfectly vertical was my thinking).......So is there a different way to get the triangulation to recognize the 2 3dp's without offsetting them?