Control Point

– You can paint weights and use a specified vertex group for mass values.
– Unassigned weights are set to minimal goal weight.
– Use Control Point weight mass to have some parts of your softbody heavier than others.

– In this example I created a group (Weight_Mass_group) where the vertex weights of the orange square are set to 1.0
– In the left video no weight mass group was assigned to the softbody.
– In the right video the Weight_Mass_group was assigned to the softbody.

– Here you can see the Weight_Mass_group (used for weight mass control point) and the Goal_group (used for the Goal to stick the borders of the soft body):

Blender Soft Body Vertex Group

Blender Soft Body Control Point