Problem in having Zigbee/XBee communication between more than 2 XBee modules.

I am working in wireless communication using XBee modules. I have done it using two XBees(1 receiver and 1 transmitter), but I am having problem in performing the communication using 3 XBees(1 receiver and 2 transmitter). Can any one kindly give me a explanation using arduino codes to establish the communication. Thanx in advance...!!!

Could you please explain more detail on how would you like to configure?

Ok, let me explain it in detail. I want to remotely control a bot using xbee protocol. In the controlling part(sender), i am sending the movement signals(Right, Left, front, back) directly from 'processing' to xbee modules using a xbee explorer(without any arduino). But to control the 'arms' in the bot i need to send the signals to xbee via the arduino. So i am having two transmitters. On the bot(remote side) I have kept a xbee module integrated with a arduino(with shield). So I am having only one receivers. Here i am facing problem in receiving the signals from both of the transmitters. I need the arduino code so that I can separately receive the values from both the transmitting XBees. Thanksss!!!!

You might need to utilize the API-Mode of the XBees.

Show your code you already have, maybe the solution is quite easy.

Arudino Xbee library

Could you please kindly elaborate it along with the arduino codes... Here I am giving the brief description of what i am able to complete till now...

Below is the processing code which is writing some integer value into the serial port. This is serial value is passed to the XBee module via the Xbee explorer.(Transmitter)

int x = 50;
int y = 50;
int w = 100;
int h = 100;

import processing.serial.*;
Serial port, port2;


void setup() {
    size(600, 400);
    stroke(0);
    fill(0);
    rect(x, y, w, h);
    
    

    String portName = Serial.list()[0];
  
    
    port = new Serial(this, portName, 9600);

    
    println(Serial.list()); 
}

void draw() {
    background(255);
      
    if(keyPressed==true)
    {
      if(key=='w' || key=='W')
        port.write(1);                      // Value is being written in the serial port
      else if(key=='a' || key=='A')
        port.write(2); 
      else if(key=='s' || key=='S')
        port.write(3);
      else if(key=='d' || key=='D')
        port.write(4);
        
    }
}

Now this is the arduino code for receiving the data at the remote side. At remote side the arduino is mounted with a Xbee using a shield.
(Receiver)

int a;


void setup()
{
  Serial.begin(9600);
}


void loop()
{
  while(Serial.available() > 0)
   {
     a=Serial.read();
     Serial.println(a);
   }
}

The above codes run fine but they are for only transmitting data from one Xbee to another. I need the code to receive data from multiple XBees. (2 as of now). Please help!!!