Good luck. I know the feeling.
Had a guy come in and cut out a hole in the coat closet downstairs just so some warm air from the heat could work its way up to the upstairs bathroom pipes.
It's worked out great, as long as we keep our coat closet downstairs slightly open, so the warm air can channel up through to the upstair walls.
Huge design flaw, but... getting warmer air up into the exterior walls has helped enormously. No frozen pipes since. And since the hole/vent was made in the coat closet/kitchen - it's worked out well.
Might be worth considering, especially on these frigid cold nights.