The House on Sunrise Lagoon — Nicole Melleby

In the third book set at The House on Sunrise Lagoon, oldest sibling Harbor must navigate spending half a summer away from her beloved home, the pull between her two families, and a growing crush on a girl on her basketball team.

If you want to get to know Harbor Moore, you need to know three things:

1. Sometimes she signs her name Harbor Ali-O'Connor to match her siblings.
2. She misses her dad a lot, but she doesn't want to be away from her moms and siblings, either.
3. She just might have her first crush.
 
Harbor is excited to spend the summer working on her jump shot in an elite basketball league. But the games take place near her dad's house -- hours away from her beloved Sunrise Lagoon. Suddenly, she's spending every weekend at her dad's and getting to know Quinn, a girl whose smile makes her feel warm inside. Still, Harbor can't help wondering what's going on at home. Why is Sam hanging out with Harbor's best friend? Has Marina's friend Boom taken her place in the house? What have the twins “borrowed” this time for one of their disastrous scientific experiments?
 
When it comes time to decide whether Harbor will stay and play basketball with her team -- and Quinn -- all year round, or continue to live on Sunrise Lagoon, Harbor thinks she knows what to do . . . but is it the right decision?