Prime procrastinator and drama queen Moxy Maxwell is about to take the stage for real, making her Piano Debut at the Palace Theater, playing “Heart and Soul” with her little sister, Patsy. True, there is the scary note from the piano teacher. But how can she practice stopping and not pounding when there is so much else to do to prepare? Once again, Gifford offers a hilarious and very nearly believable glimpse into a day in Maxwell family life. Those familiar with the first two volumes will recognize the enticing format: short, episodic chapters with long, often foreboding titles (“In Which Mrs. Maxwell Gets Back to the Point”). They may decide that twin brother Mark’s illustrative photography (provided by Fisher) is getting better; some pictures are even in focus. Sympathetic readers of any age will appreciate that, although she has just returned from Africa (bringing her own twin, the fearless, glamorous Aunt Susan Standish), Moxy’s exhausted mom is there when a suddenly faint-hearted performer needs her most. This is a solid addition to a popular series, sure to attract new fans. (Fiction. 7-11)