I thought about this. Senior management would bitch her out, and she'd probably have to stop doing it, but they won't fire her, and it would be handled discretely. That's not good enough for me. I want her to feel shame.  So I'm going to just give all the other low-level managers in my position a heads up. "Hey guys, I found out Sharon only does upstairs meetings on Wednesdays so if you need to get on her calendar, book conference room (only downstairs room), or send her an invite for a Wednesday." This will make it's way around the coffee pot before management catches wind.