Princess Luna

Princess Luna is the co-ruler of Equestria, with her older sister, Princess Celestia.

She is the aunt of Cadence, the sister of Celestia, and adoptive aunt of Twilight Sparkle. She is also the great-aunt of Twilight's daughter Sunny Belle and Skyler and Flurry Heart

Celestia
Luna loves her older sister Princess Celestia. However, when Nightmare Moon, a separate entity who possessed Luna because of her jealousy, Luna immediately hated Celestia because most of their subjects slept through Luna's glorious nights. However, after being turned back to Princess Luna, Celestia forgave her younger sister, and Luna her as well.

However, like normal siblings, Luna nad Celestia have a fight after both forgot their wedding present to Cranky and his wife.

Sunny Belle
Sunny is Luna's adoptive great-niece. Sunny affectionately calls her aunt "Auntie Luna". Sunny oftenly goes to Luna for advice when Sunny and her mother are in quarrels with each other from time to time.

It is revealed that Luna is Sunny's godmother.