try including
#ifndef HAVE_HWSERIAL1
#include "SoftwareSerial.h"
SoftwareSerial Serial1(6, 7); // RX, TX
#endif
and this may be obvious, but move Tx and Rx from the hardwired serial.
EDIT: I should have said before void setup in your code
try including
#ifndef HAVE_HWSERIAL1
#include "SoftwareSerial.h"
SoftwareSerial Serial1(6, 7); // RX, TX
#endif
and this may be obvious, but move Tx and Rx from the hardwired serial.
EDIT: I should have said before void setup in your code