You can create a decomposed process from a selection of symbols in the diagram using the Composite Process command. This command is only available from a business process diagram in which you have selected valid objects, such as processes, flows, decisions or synchronizations.
When selected symbols have input/output flows from/to non-selected symbols, a start/end is automatically created inside the decomposed process together with default output/input flows from this start to these selected objects or from these selected objects to the end.
Initial diagram:
New decomposed process:
The new decomposed process opens in composite view mode (global view of its content within its symbol in the diagram). In addition, any defined symbol custom shapes for are removed, however their relative position, size and format are preserved together with the display preferences of the initial diagram.