Using Arduino Mega 2560 Programmed and Adding Another SKM53 SKYLAB GPS into it?

Hi I am here to make certain things sure of myself, please help I will explain from starting, I have already used an code into the Arduino Mega 2560 to make it run RC Car through PC, now I want to add GPS into it with the SKM53 G229 with the GPS code, in the arduino mega 2560 can i also transfer the GPS code into the arduino mega 2560 microcontroller, with previous code already installed into the board if i transfer gps code will the whole program get erased or in order to do two separate programs i need two separate boards please help i Have done first part just need a guide on the GPS process. :frowning: