Is it possible to use APC220 to do multipoint data exchange?

I am trying to build up a sensor network which contains several Arduino boards, each of them has a APC220 or other kind of wireless module.
I wish to have all of them able to exchange data with each other, is it possible?
Data is not very much.
I know APC220 is semi-duplex, and I need to set one as master and others as slaves.
Is it possible to set it as master or slave while working by programming automatically?
Any idea or advice? Thank you~

The master could poll all slaves and any slave could send a packet to the master in the format

{ slaveID, message }

and the master acts like a sort of post office and forwards all these messages.

void loop()
{
  if (slaveHasMessage(index) )
  {
     message = getMessageFromSlave(index);
     sendMessage(message);
   }
   index++;
   if (index == slaveCount) index = 0;
}

Thank you~
So is it possible to change the APC220 agent from master to slave or from slave to master while it is running? I mean, when one APC220 receives some kind of message as a slave, it will transform to master and send out message, is it possible to be achieved by code running on the Arduino?

Thanks again~

robtillaart:
The master could poll all slaves and any slave could send a packet to the master in the format

{ slaveID, message }

and the master acts like a sort of post office and forwards all these messages.

void loop()

{
  if (slaveHasMessage(index) )
  {
    message = getMessageFromSlave(index);
    sendMessage(message);
  }
  index++;
  if (index == slaveCount) index = 0;
}

Just like your metaphor, is it possible for one receiver be the post office and post office be the personal receiver?

robtillaart:
The master could poll all slaves and any slave could send a packet to the master in the format

{ slaveID, message }

and the master acts like a sort of post office and forwards all these messages.

void loop()

{
  if (slaveHasMessage(index) )
  {
    message = getMessageFromSlave(index);
    sendMessage(message);
  }
  index++;
  if (index == slaveCount) index = 0;
}

Should be possible as it is just a serial connection. You probably need to embed it in the protocol (handshakes) that only one can be master.

Do you have a link to the datasheet?

I don't see a need for an post master, because each device will already receive all transmissions from the other devices. A master may be needed to synchronize (serialize) all transmitters. Or use kind of a token ring protocol...