The Apple herd is one of the larger ones on the steppes. This is because when an Apple marries, they usually bring in the spouse’s herd to become a part of theirs.
So when this trio of siblings lost their parents, their family had their back. When they lost their matriarch, Granny Smith, (nomad healthcare isn’t exactly the best) many of the older mares squabbled among themselves about who would take on that role. While they fought and argued, AJ did the work of the matriarch. Nowadays, she’s the defacto leader while the elders make most of the decisions in conference with each other. When they can’t agree, AJ decides.