Fairy siblings are a relatively uncommon phenomena where a laugh divides into two or more fairies. They need not be the same talent (eg, Tinker Bell and Periwinkle are tinker and ice fairies, respectively) and they can be different genders (eg, Sparkle and Glory are female, but Helios is male). When siblings approach each other or when their wings touch, their wings will sparkle. If one sibling has wing damage and touches his or her wings to another sibling's, the damage will mend.
Compare incomplete, where a broken laugh results not in multiple fairies, but a single fairy that lacks something.