Rebuilding surface from vertices

I'll start by saying I'm struggling with getting into VBscripting for Grasshopper, even though I used to use Rhinoscript a lot. But I often encounter little problems that I imagine will be easier with a few lines of code than a bunch of GH components. So here's the current challenge:

I have a surface on which I've created a diagrid. There are some "gateways" that intersect the grid that split some of the triangular panels, so I get some triangles and some quads. It's not good enough to simply split these surfaces, because I end up with one curved edge and I want all straight edges for construction.

So I just want to rebuild each split surface from it's vertices. Thought it would be simple, but I'm getting stuck. From perusing the forum I found this:

Rhino.Geometry.Brep.CreateFromCornerPoints

but I'm not sure how to implement it. I'm passing into the VB component the Breps after being split:

Private Sub RunScript(ByVal x As Brep, ByRef A As Object) 

Please point me in the right direction. I'm in the process of reading the Grasshopper primer section on scripting, but I just started. Thanks!