Cull and scale by average distance from multiple curves

I am trying to make a definition that allows me to input multiple curves, to control points in a grid firstly controlling the visible points using the Cull by distance definition; Cull & Crv CP.

Then applying a polygon to the new culled grid of points and scaling the points away from the curves, the further away from the curve the larger the polygon or the further away from the curve the larger the distance from points.  

The part I am having difficulties with is using the average distance from the multiple curves, to scale a polygon out evenly on each point, from each of these curves. 

Hope that makes sense

Any help and advice would be greatly appreciated

Thanks

Tom