This is number six in the Chrestomanci Series. I love these books. They are short, more ironic, but less complex Harry Potter-read a-likes. I found Dianna Wynne Jones looking for Potter read a-likes and found her book "The Dark Lord of Derkhelm." In "The Pinhoe Egg" you have two extended families of magicians hiding out right under the "great man Chrestomanci's" rule. The families have placed spies in the Chrestomanci household. Meanwhile the Pinhoe's gammer (female lead) has been befuddle by the Farleigh family gammer and the Pinhoe gaffer has died.
All the adults get so caught up in intriques and revenge that the children are allowed to carry on as they will (for the most part). In her attempts to help Marianne Pinhoe gives Cat Chant a globe from the attic. This begins the entire series of events: the globe hatches a griffin, curses and counter curses plague the towns, and Chrestomanci seems preoccupied.
Of course all works out for the kids. Meanwhile readers will get insights into friendship, trust, faith in others, honest, and feuds. This is a series I would recommend to children grades 4-7 depending upon their reading skills, interests, and interest in fantasy.