Who are the characters in From The Mixed Up Files Of Mrs. Basil E. Frankweiler?

From the Mixed Up Files of Mrs. Basil E. Frankweiler is an award-winning children's book that was published in 1967. It features three main characters: Claudia Kincaid, Jamie Kincaid, and Mrs. Basil E. Frankweiler. 
Claudia Kincaid is the main character. She is the one who decides to run away from home and live in the Metropolitan Museum of Art in New York City, and she is also the one who figures out how to do so. Claudia is also fascinated by a statue that originally belonged to Mrs. Frankweiler, and that part of the story leads to the end of the book. 
Jamie Kincaid is Claudia's little brother. He is financially capable because he saves all his money. This is why Claudia chooses him as her companion on this adventure. 
Mrs. Basil E. Frankweiler is a wealthy widow. She allowed the museum to purchase a statue that could have been by Michelangelo for under $500. She is also eccentric; when Claudia and Jamie show up at her doorstep, using the last of their money, she lets them look in her oddly-arranged files, and they figure out where the information about the statue is. 
There is one ancillary character, Saxonberg, who is Mrs. Frankweiler's lawyer. The book is Mrs. Frankweiler's account to her lawyer for why she wants to leave the statue information to Claudia.