Olive the alien
(Book)

"In this sweet, humorous sequel to Olive Marshmallow, Archie is convinced that his sister must be an alien! Archie loves his sister, but sometimes he is very confused by her. She speaks in a different language (baby talk), cries for no reason, sleeps anywhere, puts everything in her mouth, and is scared of bath water. There's no other conclusion Archie can make except that his sister must be an alien! But when Archie's cousin William and his baby brother Ned come over, Archie sees that all babies are like this. Archie realizes that he must have been as strange as Olive was when he was a baby too!"--,Provided by publisher.