Question about multipin port in CST MW studio

Hi, everybody,
I have a question when setting up multipin port in CST MW studio5.0.
My project is simulating a four parallel coupled strip lines with some vias on the board. My problem is how to properly set up multipin port for this kind of transmission line. You know it is hard to set the modal potential to get four orthogonal modes. And the simulator will pop up warning about this.
Using multimode port can not work correctly neither, the simulator told me it is proper to use multipin port for homogeneous port, like strip line.
Does anyone have solution on this problem? Or is there any other software that could handle this problem?
I will appreciate it if you can help me on this problem.

Any suggestion?