Desperate for a name or Author

[Tosethresee]

I recently remembered a fantastic fantasy series i read a while ago, but alas i cannot remember the title of any of the books, or the author. If you can figure it out from what i can remember i would be eternally grateful.
-The main characters were twins, a boy and a girl. The girl could heal living things with her touch but i dont recall the boys ability (if any).
-The girl brought a baby back from the dead in a small village she was visiting. The baby has no soul and fed on the life essence of anything it touched (exact opposite of the "mother". This baby grew larger as it fed on lives and soon began slowly following the girl her brought her to life, thinking it was her mother.
-They acquire a magic crown. The sister puts it on, her thoughts turn bad and she accidentally resurrects an army of previously petrified creatures. A man who can influence animals takes control of them and uses them to attack the castle the twins reside in.
Im desperate, please help!