I would call Brooke and Sierra best friends and I’d also call Sierra and Ember best friends.
Sierra and Ember share a room (since they’re so trustworthy together) and it’s beneficial for both of them. They get along so well, they don’t get crazy together (*ahem* Brooke and Sierra), and they have more time to bond together.
Ember adores her big sister and when I spot little moments like the following it warms my heart so very much. I can picture them grown and best friends, getting together with their kids… ugh, makes me want to cry 🙂