Bluetooth Modules: Two Way Communication

Hello everyone! I am currently working on a project where I have to communicate wireless wherein the Arduino Nano and Arduino Mega can send as well as receive at the same time (Both is in Master & Slave Mode).

I connected two(2) HC-05 Bluetooth modules in my Arduino Nano and two(2) HC-05 Bluetooth modules in Arduino Mega. I did this to so that I can communicate in two-way, however, even if I bound the Bluetooth:

Bluetooth module A(Master) > Bluetooth module B(Slave)
Bluetooth module C (Slave)>Bluetooth module D (Master)

they do not seem to communicate in two-way. If I only use one pair of bluetooth modules I can transmit/ receive data, however, when I use two pairs they do not communicate.

I would like to ask for help.
Thanks!

This is not exactly the code, but it operates like this:

For Nano:
#include <SoftwareSerial.h>
SoftwareSerial BTSerial1(A0,A1);
SoftwareSerial BTSerial1(A2,A3);

int state = 0;

void setup() {
Serial.begin(9600);
BTSerial1.begin(38400);
BTSerial2.begin(38400);
pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {

if (BTSerial1.available() > 0) {
state = BTSerial1.read();
}
if (state == '1') {
digitalWrite(LED_BUILTIN, HIGH);
BTSerial2.write('1');
Serial.println(state);
state = 0;
}
else if (state == '2'){
digitalWrite(LED_BUILTIN, LOW);
BTSerial2.write('0');
Serial.println(state);
state = 0;
}
}

For Mega:

#include <SoftwareSerial.h>
SoftwareSerial BTSerial1(10,11);
SoftwareSerial BTSerial1(12,13);

int state2 = 0;
void setup() {

  Serial.begin(9600);
  BTSerial1.begin(38400);
  BTSerial2.begin(38400);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  if (BTSerial2.available() > 0) {
    state2 = BTSerial2.read();
  }
  BTSerial.write('1');
  if (state2 == '1') {
    digitalWrite(LED_BUILTIN, HIGH);
    state2 = 0;
  }
  delay(2000);
  BTSerial.write('2');
  if (state2 == '0') {
    digitalWrite(LED_BUILTIN, LOW);
    state = 0;
  }
  delay(2000);
}

As far as I can see this is your FOURTH thread on essentially the same question.

also Here
Here
and here

I have already responded on one of them.

STOP multiple posting - it just wastes everyone's time. Having all the info for one project in one place makes it much easier to help.

Choose one of them and then click Report to Moderator on each of the others and ask for them to be merged with the chosen on.

...R