Ah! Good. "Boss" = "master".
Since you are in this situation:
You can "hang" the three Arduinos on a single pair of wires: A ground and a signal pulled high through a resistor. You can make the voltage and the "pulled high" whatever you need to make it to cope with the distances, etc, involved, and at each Arduino you will have simple interfaces between your "network" and the Arduinos.
(There must be a name for what I'm going to describe... someone please give it, so Wikipedia/Google searches can be done by interested parties? It is, by the way, more than is "necessary"... but if you want ultra robust....)
On reset, the master Arduino starts to do its thing... notes follow, and the slaves go into a "wait to be spoken to" mode. (Probably collecting data, etc, in the meantime.)
From time to time, the master issues a "slave A," or "slave B, talk to me" command. They (hopefully) do... and if they don't the master assumes the relevant machine is down. (see note below). No slave ever presumes to stay active on the net for more than a brief time. If it gets no reply from the master after a transmission, it doesn't retry very often.... it goes back to waiting to be "spoken to".
How do the Arduinos "talk"? They all "listen" by monitoring the voltage in the line between them. When the master wishes, or when a slave has been told to, they "speak" by pulling the line between them low in a pattern, i.e. a serial data stream. As the master is moderating the conversation, there shouldn't be cases of two units "speaking" at once. In any case, the communications should have check bytes to see that transmissions didn't fail for any reason.
You can either have the slaves reset every so often, just in case, or you can build extra circuitry which causes a reset in the slaves if the line between the Arduinos is pulled low for a "long" (relative to any other lows which will be seen) time.
All this "inspired" by what happens in 1-Wire MicroLans, and by how a pre-1960 city wide fire alarm street corner pull-box system worked. The one I knew was in Ithaca, New York, but I believe the same system was widely used... it was brilliantly simple, nearly Murphy-proof.