Modeling a parametric surface applied on a back brace

Hi everyone. I need your help.
I’m modeling different kind of surfaces applied on a back brace for my thesis using Grasshopper, but I’ve been using it for short time, so I’m not very expert.
I followed a tutorial on youtube and I got this kind of surface:


But I need this kind of surface applied olso on the brace I modeled. This one:


These are the two files (Rhino 6 and Grasshopper):
PROVA 5.3dm (15.5 MB) PROVA (24.7 KB)

I hope my explanation is clear.
I’d be grateful if you could help me.