Can I send arguments to multiple Z-wave nodes at once?

This works when just sending to node 67

msg.payload = {     
    "args": [
        { "commandClass": 112, "nodeId": 67 },
        "set",
        [{ parameter: msg.parameter, value: msg.value, valueSize: msg.size }]
    ]
    }
return msg;

But is there anyway I can send it to 67,68 and 69 all from the same function node? I tried 67,68,69 and was promptly told I’m an idiot.

Not with the CC API, unless you want to write some driver code. You’re better off getting the parameters added to the device configuration, instead of manually setting them. Then you can use multicast with configuration parameter values.