Here Comes Hortense!  (English, Hardcover, Hartt-Sussman Heather)

The feisty, irrepressible Nana we met in Nana’s Getting Married is back. And what could be more fun for a six-year-old than having your nana and her new husband take you to a theme park? But the fun is spoiled when Nana and Bob announce that they’ve planned a surprise: they are going to be joined by Bob’s granddaughter, Hortense. It turns out to be the worst surprise ever. Nana shares her room with Hortense instead of her disgruntled little grandson. She sings her special good-night song to Hortense. She goes on all the scary rides with Hortense. And, worst of all, Hortense has a special name for Nana.
 
A perceptive and hilarious exploration of rivalry, there’s a gentle lesson for readers, young and old.