The show never really specified which branch of the tree had Oranges on it, but I went with Apple Ma at least being local since AJ has been there since G1, so it makes sense to me that Sweet Apple Acres would be a matrilineal inheritance. Of course, it's entirely possible that the Oranges go further back than that, or that she left the farm for a tilt at the big city windmill just like AJ did, but she left later and brought back a beau.