To avoid colosion, i may use a 3rd wire (enable) which will be open drain so who ever wants to snd any info it will pull this wire down and will keep it down until it finishes the communication.
That won't be necessary and waste of wiring.
You can implement one master and multi slave configuration and implement some protocol like tcp/ip but simpler with adress and command, all devices listen simultaneously but only the device that has been addressed would enable its enable line and sends its data then disables its enable line.
Regards
Mahmood