When you add a subprocess to an existing subprocess, the child subprocess type is set to the same subprocess type as the parent subprocess. For example, if you add a subprocess to a BPMN subprocess, the subprocess type of the newly added child process will be automatically set to a BPMN subprocess.

You cannot change the process type for child subprocesses. The Type controls on the Implementation page of the properties view are disabled for each child subprocess.

If you change the subprocess type for the parent subprocess, the subprocess type change is also applied to all child subprocesses.

If you move a child subprocess out of its parent subprocess and onto the canvas as a top-level subprocess, the ability to change the subprocess type is restored.