okay so,
your char_select.c
Code:
#include <acknex.h>
#include <default.c>
void function1()
{
}
PANEL* pan1 //sorry, don't know how to do panels in A7, i use A6

now, call functions and panels in main code...
Code:
#include <acknex.h>
#include <default.c>
#include "char_select.c"  // your character selection code

void main()
{
   function1();
   set(pan1,VISIBLE);
}


As you can see, once you #include files, you can call the functions or panels like usual.