So according to the writer of the *Hearthbreakers* episode, Limestone is the Eldest Pie Sister, then Maud is the 2nd Eldest, then Pinkie is the next to Youngest, and finally Marble is the Youngest of the Pie Sisters, and apparently Pinkie & Marble are actually Twins because Pinkie is only older than Marble by a Few Minutes, and based off their appearances they may be Fraternal Twins instead of Identical Twins.