Annie Robbins is the younger half-sister of Quinn Robbins. At the beginning of the series she is three years old, but by Roots of Insight she is four.
Annie is the youngest child of Megan Robbins and Jeff Robbins. Her siblings are Quinn Robbins and Owen Robbins.
Annie appears or is mentioned in the following books:
Seeds of Discovery
Roots of Insight
Thorns of Decision
Blooms of Consequence
A Christmas Rose (mentioned only)
Canes of Divergence