Regarding the SparkFun Datalogger Iot – 9DoF, I was wondering how many Quiic addons I could connect to the unit at once. For example, is it feasible to connect two Qwiic ADS1015 to the same datalogger?
Sure - the main issues with adding multiple qwiic devices are:
address conflicts (hardware i2c address, 2 devices with the same address is a problem)
combined pull-up resistance (each device has a one, only one should be active per bus)
power draw (if the sensors/devices use a lot of power)
cable/wire length (too long results in too high of resistance of the bus sputters out)
That being said, 2x of ADS1015 will be fine, as the backside has jumpers to modify the address and remove one’s i2c pull-ups from being active…just keep the wiring on the shorter side 
Awesome thank you for the help!