How to make a specific area of a soft body behave like rigid body (or vice versa)? Is it possible to make a part of a soft body mesh behave like a rigid body without pinning the vertices of the object? For instance, following this answer I painted some of the vertices of the soft body object and set the soft body goal to the painted vertex group. However, this will make the object immovable and instead of the whole object, gravity will only affect the unpainted vertices. This affect could be shown better if the object weight is set to a high value. The main issue here though is the pinning; I do not want the object to get pinned to the painted vertices. Here's a gif depicting the issue:



Instead, I would like to make some parts of the soft body behave like rigid body without having the pinning behavior. In other words, I would like to vertices' weights somehow make the springs between vertices become pretty stiff so that the entire object will still fall down due to gravity but the weighted vertices won't move. 

So I wonder if you guys know a way of achieving what I want with weight painting? If achieving this with weight painting is hard, would it be possible to simply assign soft body to some of the vertices of a rigid body instead?\

Here's a .blend file that you can begin your work with; I used Blender 2.79b for this work:
Although it seems impossible to make a part of the mesh like a true rigid body, but following cgslav comments I could do this to some degree by assigning the vertex group to Springs as shown below. Note that the object is a bit heavy (10kg) and that's why assigning weight 1.00 to the vertices will still result in them moving a lot. Assigning lower weight values to the object fixes this issue to some degree and that is sufficient for my work.