Umm, first of all, the Windy Boys I'm aware of can't handle this sort of power (56V x 26A x 4 = 5.8 kW).
Second, diversion controllers only work with a battery system. Without a battery, the voltage will not be stable enough for the PWM (it doesn't test the voltage instantly, in fact, many users have complained when using the Xantrex as a diversion controller because of this reason; MorningStar's TriStars are better in this respect).
Third, if you could connect the controllers in series (please, please, do not try this), this would mean that only one would be able to be grounded, and you would be left high and dry in electrical storms.
For this type of thing you could use a FlexCharge NC25A, which is not a PWM controller, but a 0%/100% (slam/bang) relay controller. Although you can only get nominal 12V/24V/48V systems, it's quite easy to attach the sensor to only 2/4/8 6V batteries in a string (if this is what you have) or use a resistor divider to adjust the input voltage into its range. You then need suitable relays rated for the voltage (and current !) you need to divert.
However, my advice from what you have written (please do not take this the wrong way; I really have your best interest at heart and do not mean to be condescending) is to take yourself to a local renewable energy dealer and follow their advice.
Best of Luck,
Dave