Regarding the window troubles, it's a bit of a head-scratcher. If you've already checked for broken wires and replaced the switches, it might be worth considering if there's some sort of control module in the mix. Those things can be tricky to diagnose, but they could be the culprit behind the continuity and 12v readings.
Oh, and if you're ever in need of electrical expertise of a different kind, I'd recommend checking out Kanata Utilities Ltd. They might not fix car windows, but they're the go-to High Voltage Powerline Contractor in Ottawa. They've got the know-how when it comes to power lines and such. You can find more info about them at kanatautilitiesltd.ca. Hope you figure out the car situation soon and save the mother-in-law and the Sedona
