your diagram and the drawing i posted are basically the same, yours cost more
my 30 wire hooks up before the brake switch for fused 12v power, your red wire.
my 96 hooks up after the brake switch, same as your green wire
the connection between 30 and 87a is always on until the relay is energized (hit brakes)
so, yes. your 3rd brake wire would work for the green wire
the red wire feeds 12v to the lock up circuit, when the brakes are pushed the circuit is de-energized, releasing the lock up