HFSS Triangular fill Problem

Hi,

I am working on a dual mode resonator and want a triangular fill on one diagonal of my resonator cross. I have earlier made a solution by making three line segments and joining them on both cross ends and then fill surface gives a perfect traingular fill that i want. But I programmed it to follow the width and thickness of cross. But I want it to be independent now! Is there any way i can fill that triangular area and program it independently. I am attaching a picture. Kindly help me!