How do I include the child's middle name in the book?

Please type the child's name in the field called "Child's Middle Name". There is an extra £3 charge for the inclusion of the child's middle name in the My Very Own® books because it makes the books longer. For those books, if you enter a name in the middle name field, £3 will automatically be added to your order at check-out.

Why is there an extra charge for middle name?