Parallel execution of Sub-Processes so that one doesn't wait for completion of others even if they involve Human Tasks

Issue

• The scenario involves a main process with multiple Sub-Processes (could be Embedded or Ad-Hoc) running in parallel, with no execution sequence relationship required. The number of these parallel Sub-Processes is not fixed. The execution of each of these Sub-Processes generally involves Human Tasks, and the engine should not wait until a Human actor responds to the request, but instead continue and process the other parallel Sub-Processes.
• Can this be achieved in jBPM 6 ? If so, which of the below Sub-Process types would suit the requirement best?
  • Embedded Sub-Process
  • Ad-Hoc Sub-Process