I know these PG kids can go rapidly through reading lists and library collections. I've got some suggestions:
1. Have you had a look at Library of Books (
http://www.bookslinksandmore.org/) suggestions? She has two PG kids. So there may be something your DS hasn't read yet.
2. Have you tried the following books:
The Giver; Fahrenheit 451; Carry On, Mr. Bowditch (FYI - a number of people die due to life at sea and early 19th century)? Those are rather serious books. Dahl is my favorite for the humor. Terry Deary's Horrible Histories are pretty good though, if you like that humor. Terry Pratchett has a lot of books that might work.
Paulo Coehlo's The Alchemist is a good read too.
3. I recently read Conor Grennan's Little Princes book on orphans in Nepal. It was a very inspiring and moving book, I thought. It's a non-fiction memoir, but it might appeal to your daughter. Of course, she might want to fly off to Nepal after reading it though.
I do have to agree with you on the content and problems over fiction with a PG child reading so ahead. It's rather challenging finding appropriate material in the YA section; there's so much that is inappropriate. I'm relieved my PGlet has turned to non-fiction. That makes it a tad easier.
