The player that controls the Top-Most Card that changed zones decides the order these cards Detach in, and thus the order of any relevant effects that occur due to the Detach occurring.
§ 719.5.a Core Rules PDF (officieel)
§ 719 A Top-Most Card is a card that has one or more cards linked to it through the process of Attaching.
§ 719.5 When a Top-Most Card changes zones from a board zone to a non-board zone, all Attached cards Detach from it, remaining in their current zones.
