Rhombus trim on triangle plane surface


Beeing new to GH, I have a question that concerns list management and surface division

I’ve been trying to create the lines that are depicted in blue in the first image on a triangular plane. My purpose is to have a trimming with this rhombus pattern on top and triangle at some border. Also, i can’t manage to take away the lines that are on the surface edge.

I’ve been trying with relative items, cull list, sub list, doing manually lines, isotrim with domain division UV but nothing works.

Could somebody help me?

Thank you in advace