During training as a fireman and emt I had an opertunity to listen to a recording of the firemen, cops and others on 911. Communications were useless. You could not tell what was going on with everyone yelling into their radios and it just got worse until the end. In a disaster the first thing to go is communications because of overload.
What we determined was that before the event have as much as you can, worked out. Places to meet, to go, to leave messages, times to meet, ETC.
I dont know of anything that would be fool proof and with comm. others you may not want to know, would know where you were.