including libraries.. into libraries

It might (probably will) be a lot easier if MenuLCD derived from LiquidCrystal.

Then, you could initialize the base class using
MenuLCD::MenuLCD(a bunch of args) : LiquidCrystal(most of those args)

Then, since this (a special C++ variable) IS an instance of LiquidCrystal, you could simply

this->print(someMessage);

(Or, the this-> bit is not really needed, so just print(someMessage):wink:

If this is too complicated, just make lcd a global variable, declared in the header file, outside of the class definition.