Well probably the easiest way I can think of would be to use a distort map, but that would mean breaking collision detection, unless you use a canvas.
Thing is your getting an error from your current method, possibly something to do with "is falling" in conjunction with "system create object relative to object", so your probably going to have to figure a different set of events for that.
As for using a distort map the easiest method might be to set the x,y of a vertex a certain distance from the center when you either A: have so many top objects, or B: use the distance of the player from a certain point to control it.