You can merge two or more contact regions into one contact region, provided they share the same type of geometry (edges or faces).
To Merge Contact Regions That Share Geometry:
Select two or more contact regions in the tree that share the same type of geometry (edges or faces). Use the Shift or Ctrl key for multiple selections.
Right-click to display the context menu.
Select in the menu. This option only appears if the regions share the same geometry types. After selecting the option, a new contact region is appended to the list in the tree. The new region represents the merged regions. The individual contact regions that you selected to form the merged region are no longer represented in the list.