The Fairy Bell Sisters: Rosie and the Secret Friend by Margaret McNamura

Sheepskerry Island is a fairy's paradise in fall and winter and spring, but not in summer. That's when the cottages are taken over . . . by the Summer People. Tinker Bell's little sisters, Clara, Rosy, Golden, Sylva, and Squeak, spend the long sunny days in hiding. The Summer People are dangerous! But one Summer Child, Louisa, needs a little extra help this summer, and kindhearted Rosy knows just what to do to make her feel better. Soon Rosy and Louisa are secret friends! But what if the Sheepskerry fairies find out Rosy has made friends with a Summer Child? And how can Rosy keep such a big secret from her very own sisters? Read all about the magical adventures of Tinker Bell's little sisters!