parent or constrain vertex groups

Is there a way to parent or constrain a vertex group to another object. For example create a cloth object, designate two corner verticies as a group and “pin or constrain or parent” them to another object like a sphere to animate the sphere.

I Found the following located here

For Meshes and Lattices, there is now the option (“VG:” field where applicable) to specify a Vertex-Group to define the target of a constraint.

However when I select my sphere to put a constraint on it, I don’t see any options to constrain a vertex group, only the full object.

Can this be done in 2.53

thanks