Master for submasters

Is there a way to make a master for submasters? I would like to limit a set of HTP submasters. 

This could be useful if someone is busking but the set is recorded for television and there is need to limit the output of certain sets of light.

Also useful when you are controlling submasters from remote OSC and you need a way to temporarily disable this with a fade and also without switching off all OSC input.

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