Help with classes

My C++ is very rusty, having used Delphi in the last decades. Now I need some advice/assistance with this project:

I have constructed an stand-alone Arduino with an LCD display, which I want to use as an output device for other Arduinos. The display system can receive commands via serial or I2C, no problem so far. Now I want to create classes compatible with the LiquidCrystal class, which can provide virtual LCD objects, say LCDSerial and LCDWire. How must the interface (header file) and implementation look like, when these classes shall offer the public methods of the LiquidCrystal class, but override these methods to use the Serial or Wire class for data transmission?

What changes are required to e.g. the CrystalBall sketch, when the detached LCD display is connected via I2C?