Yoga for Kids and their Grownups by Katherine Priore Ghannam- This book would be great for the whole family. It has illustrations of many poses as well as sequences .
Just Breathe by Mallika Chopra - This would be a great book for kids 9 and up to learn about different breath practices, guided meditations and poses.
Playful Family. Yoga by Teressa Asencia- This book is great if you prefer photos and it is full of partner and group poses for kids and adults.
Yoga for you and your child by Mark Singleton- Also great photos of poses, as well as games, breath practices, guided mediations and sequences.
*Please note some of these books may be out of print. You may be able to find gently used copies at www.thriftbooks.com, Third place books or other used book stores.