The Ring of Shooting Stars has the Shooting Star effect as described below:
Shooting Stars. You can expend 1 to 3 charges as an action. For every charge you expend, you launch a glowing mote of light from the ring at a point you can see within 60 feet of you. Each creature within a 15-foot cube originating from that point is showered in sparks and must make a DC15 Dexterity saving throw taking 5d4 fire damage on a failed save, or half as much damage on a successful one.
My question is can the motes be layered on top of each other to form a cube, wherein each creature must make 3 x DC15 Dexterity saving throws and be subject to 15d4 (modified by the saving throws) damage?