Help with device identification in a chain
It would help to know what phy layer you're using. But, here's some general information:
If you're using I2C, your bus should look something like this:
(taken from societyofrobots.com)

At runtime, you can detect the I2C addresses by scanning the bus by sending a START condition to every address and checking for an ACK.
If you're using SPI, you'll need a chip select line per device. If you run out of pins, you could use some kind of multiplexer. You may be able to scan the bus by asserting each chip select line in turn and attempting to communicate.
http://kkamagui.springnote.com/pages/422905/attachments/177111