I haven't checked there yet, and someone also PMd me some pretty helpful links regarding this, detailing how to communicate between multiple devices using i2c (and another protocol I hadn't heard of), so it certainly seems that's the next logical place to look. Thanks!
The links are here: Gammon Forum : Electronics : Microprocessors : I2C - Two-Wire Peripheral Interface - for Arduino
And here: https://www.gammon.com.au/forum/?id=11428