Editing surface ends in x, y, and z direction

Hi there,

I have edited this GH file to fit the needs of my design. The editable points on the surface edge currently go up and down in the z-axis. I also want these ends to move on the x and y axis.

I’ve been messing around with this file for a while, any help or ideas would be greatly appreciated. I am new to this program and hope to learn if you can point me in a good direction.

I’ve attached the file and a sketch.

Tent - Editable - 8-31.gh (40.5 KB)

Thank You!