Morph Deformer Falloff On Object Hierarchy

I am wondering about the function of the Morph deformer.

I know how to set up Pose Morph on something like a single sphere and then modify the sphere’s geometry with different poses. I see how to use the Morph deformer with falloff to, for instance, use a linear falloff to blend between two of those poses.

But I was interested in whether or not the Morph deformer falloff could apply to a hierarchy of objects.

Here is an example of what I am talking about.

Three Spheres under a null with a pose morph tag.
The pose morph has two poses.
The only difference between the poses is the position of the spheres.
I want to animate between the two positions.

So far, all the above I can set up no problem.

BUT

I want to control the blend between the poses using falloff so that, for example the spheres begin to move from left to right.

I cannot get the Morph deformer with falloff to do anything to the above setup.  Is it not possible?

Thanks,

Lance

P.S. I know that I can do the above with Inheritance but am wondering specifically about the morph deformer.