Configuration of XBee network with multiple end devices
The sensor XBees won't interfere with each other. The mode depends on if the PC needs to send data to the sensors.

If it doesn't (all data is one-way), you can set the sensor XBees' destination address to the PC one's address.

If it does, and it is ok for all the sensors to get the same message, you can configure the PC XBee to broadcast.

If the PC needs to send messages to one sensor at a time, use API mode (or configure the destination address on the fly, entering programming mode might be too slow).