What about linking them together on the opposite side of the unloader valve, or before the unloaders. Then Bolck the outlet of one machine and connect the wand to the other machine. So the unloader with the lower settings will automatically do the Job. Of course you must make sure the unloader that is set on the lower pressure can handle the flow. There would be no need for adjusting the Unloader valves. You would only need to change the nozzle. If the unloader set to the lower pressure can not handle all the flow you would have to adjust both Unloaders to the same pressure and then this whole setup would not have much benefit. What do you think about this Idea?