How to make blocks change over a certain height

[drafting3]

Hi all,

 

I have a dynamic block of some door hinges. Depending on the height of the door, depends on the type & quantity of hinges used. I was wondering if it is possible to have a block that detects height? If I insert the hinge block onto my drawing, and snap the base point of the block to the bottom left of the desired door, stretch the pick point to the top, I would like it to automatically change from 2x small hinges (for doors under 312mm high), to 2x large hinges (for doors under 1000mm), and finally to 3x large hinges (for doors over 1000mm)?

 

I have attached a PDF for visual reference to what I'm talking about.

 

I have no idea on any 'Lisp/VBA/Scripts' in AutoCAD, so any suggestions would be greatly appreciated.

 

Thanks, drafting3.