Gerald McGrew is the main character from the Dr. Seuss book, If I Ran the Zoo. He is not related to Mayzie McGrew. In his mind he owns the McGrew Zoo. But instead of running a regular zoo that has has animals like lions tigers bears snakes cheetahs, elephants, normal kinds of birds and monkeys. Gerald decided that he would want something better than that cause you see animals in any other zoo around the world. So he goes on a journey to find animals that are way different of a breed than any other regular animals of the jungle.
The protagonist of Judy Sierra's Wild About Books is Molly McGrew, a tenacious librarian who parks her bookmobile into the Springfield zoo and inspires the animals to read and write their own stories. Once reading catches on, she sets up a branch library at the zoo which the animals eventually run themselves. Perhaps Molly McGrew is a relative of Gerald McGrew - there are several Seuss references in Wild About Books, and the book itself is dedicated to Theodor Seuss Geisel.