348P: Island Mystery

Main Character is a young woman hired to be a companion to a teen by the teen’s guardian. Takes place on an island that you have to take a ferry to the mainland. The teen goes missing and the guardian’s younger brother says she ran away and he cuts off his hand to cover up the murder scene. There is a scene where they make oatmeal by leaving it on the stove overnight. The companion starts to be attracted to the younger brother but discovers what he did.

347R: Kids hunt for a treasure at a lake only to find it’s confederate money

I read the book in grade school in the early 80's.

I remember it's a mystery book where kids visiting a lake look for a treasure.  In the end, the treasure turns out to be worthless confederate money.  One scene I remember vividly:  The boy is tricked by the girl to swim to the bottom of the lake with his snorkel and look up.  She claims it's a beautiful view.  When he does so, the protective valve on the snorkel opens and water floods into his mouth.

I also seem to recall a dragon on the lake at night, but it's made of paper and burns up from the candles used to illuminate it.  It is possible, however, that this memory might be from another book...

346P: Teen Mystery Centered Around a Library (Solved!)

It’s set in a small town where the main girl is a young teen/pre-teen and she lives with her grandparents and her uncle who is younger than her and is basically her little brother. They go to the library in town (the mystery of the book is centered around the library) and the library has a large mural of Andrew Carnegie burning in hell because the town hated him and refused one of his Libraries and built their own with a big “f you” to him in it.

345U: Virgin Islands young adult mystery (Solved!)

I am searching for a young adult mystery that was set in the Virgin Islands.  The protagonist, a young woman, receives a message from her father on an alphabet shell.  I think it was her father, who is a doctor, and who has been abandoned on an island.
Please help me.  This book was a seminal influence on my desire to live on islands. I now live in Manhattan.

340Y: Hidden Paintings and Blueberries

I am looking for a children’s mystery book about several siblings who are spending the summer in an old house and find several paintings hidden in the house by a deceased but famous painter. It seems as though their grandmother is with them and they spend time picking blueberries. I thought the name of the book was Blueberry Summer or The Blue Boy but these titles don’t match the book I remember. The book is about 50 -60 years old.

338O: Girl searches for spinet-playing doll (Solved!)

I’m looking for a book that was written probably in the 1960’s, possibly early 1970’s.  I think the title contained the words “secret friends”. It is about a girl and her best friend who stumble across a mystery involving 2, or maybe 3, mechanical dolls. Her father owns an antique store. He has one of the dolls, a girl sitting at a desk who dips a pen in an inkwell and writes. The other is a girl playing the spinet. I remember the clue to the mystery was found inside the doll.

338I: Kids trapped in house, chased by a mummy and Anubis

I am looking for a children’s book I read between 1985-1988. Maybe a scholastic book. It had a dark yellow paper back cover. It was a mystery book. It was geared for the 3rd to 5th grade crowd.

It was about a boy and a girl (siblings maybe) that were trapped in a house.  There was a mummy and a statue of Anubis that came alive and chased them around the house. The whole book took place in one night

Please help me. I have been going crazy trying to remember!

338A: The Mystery of the Missing Twin (or maybe sister)

This is a kids mystery book, probably written in the early 70s.  The author’s last name was at the end of the alphabet–Mayba a W.  
Two sisters–I think twins, but they may be triplets, where two are identical and the third isn’t.  The girls are on vacation in either Newfoundland or Nova Scotia.  They run into another girl who looks exactly like one (or two) of them.  the non-identical sister is convinced she’s adopted, and that the girl they saw is the actual twin (or triplet) of the others.  They try to find the girl again, but she’s been kidnapped.  
There’s a whole mystery involving caves and some missing jewelry? The parents are kind of cagey about why they’re In Canada, so they’re not a lot of help, although they are present. They’re at a lawyers office quite often, giving the girls unsupervised time.  They use the resemblance between the kidnapped girl and the sister to trap the crooks somehow, with the fathers involvement.

At the end, it’s revealed that the kidnapped girl is their cousin, which is why she looks like them. I think the parents were trying to arrange to adopt her.
I’ve been trying to remember this for awhile, but can’t.  Googling just brings up a lot of results, which aren’t helpful.
Thanks for any help!