Go to the library and check out The Savage Garden. Then you can show her where it details how the plants should be watered, species by species. Arm her with information and then ask her to trust in you that you really know what you are doing.
If you want a firsthand "This is how this plant SHOULD be" kind of thing, then you can quote me with this: "A properly watered Venus Fly Trap, Sarracenia and most Drosera should have soil damp enough that when you pick up a bit and squeeze it in your fingers, water should run down your hand and arm like grease from a really good cheeseburger." My plants all stand in trays with water from 1/2 to 2 inches deep or more.
Good luck,
Steve
EDIT: It should be noted here that what Ozzy said is very important. Yes, some of my plants are sitting 2 inches deep, but they also use all that water within 24-48 hours (less in mid summer). So while they are filled to a couple inches deep, the next day they are nearly ready for water again.
Steve