House Kryze was a Mandalorian family that appeared during the Clone Wars period. In other words, it was almost like the royal family of Mandalore. The head of the family was Satine, who served the planet as its duchess. She had a younger sister, Bo-Katan, and an unknown sibling who was the parent to their nephew, Korkie.
The Kryzes were all different in personality. Satine was a Pacifist and led the New Mandalorian government to be peaceful. Though, she was not without her faults as she entered a secret and forbidden relationship with then-Jedi padawan Obi-Wan Kenobi.
Bo-Katan was the polar opposite of her older sister and was deemed a rebel especially when she joined forces with the zealots known as Death Watch. Despite their differences, Satine referred to her sibling as simply, “Bo.”
Through their unmentioned and somewhat unknown sibling, Satine and Bo-Katan were aunts to Korkie who was fiercely loyal to the duchess, affectionately dubbing Satine as “Auntie Satine.” By the time of The Mandalorian, it is unknown what the young Kryze’s fate is, as his last surviving aunt, Bo-Katan, says she is the last of her line.
Whether Korkie is deceased by this point in the story is unclear, but it’s possible that Bo was talking about leaders in their family. Her sister has been dead for over twenty years at this point in the timeline. Maybe she was referring to how she lost the Darksaber without having to actually reference it.