Network Discovery with S2C XBee

I have setup three XBee S2C modules in API2 mode with firmware ZIGBEE TH Reg 405F. They are all in router mode, because I want to create only point to point communication.

All I want to do is to scan any available network to join. I do not care how many XBee modules are around or their addresses. Just a quick rough scan. what is the simplest and easiest method?
So far I have been using ATND -> 7E 00 04 08 01 4E 44 64 but unfortunately this command interrupts all XBee modules that are already busy communicating with other XBee modules.
ATAS -> 7E 00 04 08 01 41 53 62 didn’t work for me!
Is there a simpler way to scan for any module around?

One other question. Let’s say two XBee modules are communicating with each other, and a third XBee module comes around looking for an XBee module to pair with. Is it possible to scan in a way that the third XBee module doesn’t see other XBee modules that are already busy communicating?

Thanks

Assuming they have not already joined, a router and end device automatically are searching for any and all networks in which to join that meet the SC, ID and ZS parameters.

That is to say, you don’t control the active scan function and have to select which network to join. The module does that all on its own based on the settings you have provided.

The ND or Node Discovery command is used once you have Joined a network to see what nodes are on that network.

Is there a way to configure the S2C XBee Modules to act similar to Bluetooth modules when pairing? In other words, can I search for available(unpaired) modules nearby, pair with them, and start communicating? What I like about XBee Modules in contrast with Bluetooth devices is that I can communicate using the 64-bit unique MAC address.

That is dependent on the application you write and what commands you use and not the radios. That is to say, the radio is ready to send and receive as soon as association or Joining occurs. It is dependent on the external application that you create that depends on when communications occurs.