Surface borders- not moving them when modifyig surface

I have a problem with keeping the perimeter (borders) of the surface fixed. I created a hexagon and then patched this so that surface is created. I can modify it by means of the grid with control points but then also the perimeter hexagon looses its edges and i need them firm at 0 (it will be the roof). How can I do it?

Hi Joalem - see if this gets you pointed in a useful direction -

PatchHistory.3dm (189.0 KB)

  1. Hexagon
  2. Line (red) from the center to a vertex.
  3. ChangeDegree to 3
  4. ArrayPolar the line with History on.
  5. Patch all curves, with History on.

Now turn on points for the red curve and move the points.