Puppy is a big fan of some of Cathryn Falwell's other books, and he likes the characters in We Have a Baby as well. This was our "love the baby" book. Each page shows the older sibling "helping" to take care of the new baby: holding clothes while dad changes the baby, snuggling with mom while she nurses the baby. It reinforces that the family is one unit and the sibling is part of caring for the baby. The text is sparse and simple. This book gets also bonus points for the vaguely multiracial family.
The New Baby by Mercer Mayer starts rather abruptly with the parents going off to pick up the new baby, which is exactly how I imagine a sibling's adoption feels to a two-year old. It's a basic story of a sibling being annoyed that newborns aren't instant playmates, then realizing that there are some fun ways you can interact with them. I am totally creeped out by the strange animals in Little Creature books. But this is one of Puppy's favorites because he likes showing off Firefly to his friends the way the older brother shows off the baby in the book.
I'm a Big Brother (there is also an I'm a Big Sister version) by Joanna Cole. I would not have predicted this as a winner, but Puppy likes its theme of big brothers being able to do all sorts of things that babies can't (eat ice cream,walk, play). The transition from "baby" to "big boy" has been a frequent topic of conversation in general at the developmental stage Puppy is in, and this book fit into that nicely. It has the same matter-of-fact tone that I appreciate in Cole's book on adoption.
Peter's Chair by Ezra Jack Keats is about a big brother feeling displaced as things from his babyhood are redecorated and reused for his new sister. Peter makes one final valiant attempt to save his special chair from being handed over. Keats is a good storyteller and he takes Peter through the process of accepting the changes in his family life without being didactic. We reused most of our baby gear, so this was a big issue in our household, too.
What the No-Good Baby is Good For by Elise Broach was our counterpoint to the lovey-dovey books. When the big brother declares that "the no-good baby is good for nothing" and should be sent away, to his surprise their mother agrees and starts packing up her things. As he considers the possibility that baby might be gone forever, he realizes there are some things he actually would miss. By the story's end, he decides that the baby should stay, but also gets to spend some alone time with his mom while the baby is (temporarily) sent away with grandma. I wanted Puppy to know that it was okay to not love the baby all the time or right away. His world was turned upside down without his permission. I wouldn't expect him to only have positive feelings about that. I liked that the older sibling's expressed need for attention is met in this book, instead of disappearing as he realizes the baby is kind of fun.
You probably noticed that none of these are about adoption. Adoption was already a familiar concept in our little home library and in our family life in general, so we weren't hunting for books that explained adoption. We just avoided books that made pregnancy part of the storyline and instead looked for ones which focused on the transition of adding a sibling.
Finally, all the books mentioned show two-parent, heterosexual families. Which worked fine for our household, but obviously might not for others'.