Maybe change Chewie's name?
I would try setting her up, with tidbits sprayed (soaked) with bitter apple, or if she likes bitter apple, maybe try 1 drop of tabasco. Not more than one drop, even then I know that is harsh, but eating things can kill her.
I do know a very small dog who died after ingesting very little chocolate, and a huge dog that died after eating a second dishrag. And another small dog who lost half his intestine to eating a piece of round plastic (from a milk jug).
Start to leave pieces on the ground, and drop the doctored things on purpose without saying anything, don't look at her, don't make any point to it, don't acknowledge.
A cherry stem, or eraser would be perfect. Something that will really soak up bitter apple would be good, and keep doing it. Percentage wise if more of the things she grabs taste bad than good, she may learn something?
Honestly it doesn't sound to me like she is "trying" the benedryl just tasted bad. Dogs don't "try" to be good unless they understand the concept
As far as your DD goes, I would put up a baby gate, and she can leaves things laying anywhere she wants "in that room only". BTDT
When setting up the gate, try to (without shame) explain to why it is going up, and try to help her to understand how horrible she would feel if Chewie became very ill, or died after ingesting one of DD's things. I would hate for my child to learn that the hard way - much less how horrible it would be to lose a dog that way.
Looks like you are getting good advice, I hope something clicks. Good luck