The only way to have them the creator is for them to import the world
into a new world. You would loose high scores and likes, ect. When they
make a blank world, navigate to the world you want to import, on the
world page choose import world. They wi...
One option would be to set "set object physical motion " to false when
they release it, that way when they lower one is grabbed the physic
engine will not send the one on top flying. This will stop it from
falling down if the lower blocked is removed...