Fantasy novel with that world's version of a gypsy

[maidmerien]

This has been driving me nuts for years. It's a book I read when I was a little girl. All I can really remember about it was one of the two main characters was a gypsy and she could tell fortunes. I remember that she was better at it than her mother and she could do magic through meditation - breath in one nostril and out the other. I also remember the book started with the villain going to visit the girl and her mother to get his fortune told.

I think there was a second character who was a boy and there was an adventure to save their world or kingdom or something similar. I know it's not a lot of information, hense me never being able to find it on Google. >.< Any points in the right direction would be wonderful.

A cassette book about a brother and sister

[mzi]

I don’t remember much but I do remember it being on cassettes and a brother and sister who wrote and illustrated awful stories that their parents hated, they use the bedroom wall as paper and their parents send them to a school for troubled children that has tornados around it so they have to wear cement shoes when they walk around the school
Please if anyone knows it, please let me know! It’s been driving me crazy for years