How do I send/receive data from hc-05 to esp8266

Question

I have connected hc-05 bluetooth module and Esp8266 wifi module to my arduino uno. This is my code

#include <SoftwareSerial.h>// import the serial library

SoftwareSerial BluetoothModule(10, 11); // RX, TX

int ledpin=13; // led on D13 will show blink on / off
int BluetoothData; // the data given from Computer

void setup() {
  // put your setup code here, to run once:
  BluetoothModule.begin(9600);
  BluetoothModule.println("Bluetooth On please press 1 or 0 blink LED ..");
  pinMode(ledpin,OUTPUT);

}

void loop() {
  // put your main code here, to run repeatedly:

   if (BluetoothModule.available()){
        BluetoothData=BluetoothModule.read();
        if(BluetoothData=='1') {   // if number 1 pressed ....

            digitalWrite(ledpin,1);
            BluetoothModule.println("LED  On D13 ON ! ");
        }
        if (BluetoothData=='0'){// if number 0 pressed ....

            digitalWrite(ledpin,0);
            BluetoothModule.println("LED  On D13 Off ! ");
        }
    }

  delay(100);// prepare for next data ...
}

As you can see the code is fairly simple ( taken from instructables.com ) And it works fine .I am able to send "0" and "1" from my app and the LED goes on/off.

I have also added ESP8266 wifi module to my arduino and I am able to send AT commands . Here is what I do :

1) Open Serial Monitor

2) Set Baud Rate as 115200

3) Switch to CL and NL 4) Start sending AT commands from Serial Monitor and it works fine.

=======

Now my next approach is to receive single character like "a", "b" and then forward this command to ESP8266.

I tried creating a software serial on 8,9 (RX,TX) and tried forwarding "a" as "AT" to the module and receive data from ESP8266 to bluetooth module but that did not work.

if( data == "a" ) {
    ESPserial.write( "AT");
    Bluetooth.println( ESPserial.readString() );
} 

How can I share data between hc-05/esp8266 wifi module ?