Static functions are local to the file in which they are defined. They are not globally visible at all. Even if you include a function prototype in a file, it will not be able to access the static function. Only functions within the static functions file may call it.
If you need to work with Microchip Support staff directly, you can submit a technical support case. Keep in mind that many questions can be answered through our self-help resources, so this may not be your speediest option.