Congratulation Message On Baby Books Instead Of Cards At For A Baby Shower?

Books instead of cards at for a baby shower? - congratulation message on baby

My cousin asked, instead of buying them a card to go with a gift that everyone prefers to buy a book with your child to go with the gift. He added that if the right to a special message inside the book and sign as you would with a map. In a card to write something in the sense of "Congratulations on your baby and my best wishes." But the book is for the baby, I am about what I write, confused. Has anyone an idea?