Like pretty impossible meaning there are no round things in Mythruna anyway, so getting something to balance on a point like that is not possible... let alone the dexterity it would require to place the objects on top of each other so perfectly that their x,z coordinates match exactly, rotation exact, etc... else it's a really small possibility (like winning the lottery small) that moving the lower object wouldn't disturb the upper one... since they are probably already interpenetrating slightly anyway.
Only the spheres can be so perfect.
And at any rate, there will be other ways to get the physics to do strange things, I'm sure. Even in Skyrim I've seen the physics do some totally ridiculous bonkers stuff... I love it every time. Makes me feel better.