I think that Book 2 would be a better fit for her, but only you know your daughter and her capabilities.
Book 1 is more of an exploration of the numbers through 100. Book 2 includes some review of Book 1, then the student builds each addition table in turn and works addition and subtraction problems that come from that table. Facts from each table are reviewed throughout the book. After several of the addition tables are learned, multi-digit addition/subtraction with carrying/borrowing are introduced formally. In Book 1, the student solves problems with carrying/borrowing but in a more exploratory way. Book 2 also covers the multiplication tables for numbers 2-6 and division based on those tables. Lessons in both books are short and mostly oral with minimal writing for the student.