Question : Problem: Connecting power supplies of different voltages to same ground

Is it possible to connect power supplies with different voltages to the same ground or will this mess thinfs up.
Also, if I have a 9 volt battery and a 1.2 volt battery, can i connect the minus poles and drive 9v things with positive from 9 volt batt and to the common minus and 1.2 volt thins from 1.2 plus to common minus?

Answer : Problem: Connecting power supplies of different voltages to same ground

yes , you can do that; but i would NOT interconnect the devices you hook on those different PS