SOLVED!: ya novel about brother and sister orphans [s]

[KJP]

I am trying to remember a novel about brother and sister orphans, they lost their parents in a ferry accident. The sister is a witch (supposedly) and they two are sent to live with some wizarding family. It turns out that the brother has the true powers and the sister gets stuck in some alternate reality (i think).

[Deb]

This is Charmed Lives, by Diana Wynne Jones, part of the Chrestomanci series. I just re-read it two weeks ago, and you have remembered the plot very well!

[KJP]

Wow- Thank you so much!
I took it out as a book on tape--maybe a year or two ago--didnt realize that it was part of a series!
THANKS

[KJP]

Not sure how I edit the title-- but the mystery is solved :)