[Michael C Henry]

So what you'er saying is -power to dash switch switched by ignition switch-power for park supplied to wiper motor not switched by ignition switch. That's doable. The result would be if you cut the ignition before wipers park ,they will go ahead and park and you wont have to turn the ignition on again to let the wipers park.
I still do not see the ground switching .Their is no ground shown at the Dash wiper switch.When the dash switch is in a park-off position and the wipers haven't come to the park position .Power supplied that is at the motor park cam operated switch is sent back to the dash switch via the park wire.That is internaly connected to the low speed inside the dash switch when in park -off position. That power is returned to motor via low speed. and is interupted by the wiper motor cam switch when park is reached.