Harriet Matirni and the Wizarding World

With the help of James Thurber's "The 13 Clocks," Petunia, a squib, convinces Severus to help her find alternative magical education. He locates the Matirni Traveling Circus (& squib school). She lives happily ever after (and willingly takes in her little sister's orphan. Who happens to be a metamorphmagus. Plotting ensues.) (Multigender!Harry)