Al, many thanks for the brainstorm.

Thinking out loud here....

I see where I was getting hung up, the "ack" and the addressing.

My xbee's are series-1 so as long as my remote sensors set the xbee [DL] value to the xbee coordinator [MY] value they'll talk point-to-point, which is what i want.

I can prefix an incoming data packet with an "identifier" so the coordinator knows which remote and thus that data is to follow. And when the coordinator recieves data along with an end of message character I can have it send an "ack" back to the sending remote thus qualifying the data sent.

I can see where I was stuck in my thinking, thanks for clearing the picture.

Cheers!