Yes, we are working on support for sub-processes in the Oryx Designer. Fix should be available in the next version.
The new BPMN 2.0 Eclipse editor already allows you to specify executable BPMN2 processes that can be executed on jBPM5. We're still working on improving the usability though. Because at this point, it is exposing all constructs at a rather low level, so creating service task data input and output (or mapping) is possible if you know how to define those in BPMN2 but requires detailed knowledge of the BPMN2 spec. We'll be working to offer all constructs at a higher level (user for example a graphical data mapper UI) so these internal details can be hidden from end users. Once that is done, the new BPMN 2.0 Eclipse editor should replace the old tooling.
We're targeting this to be ready for the next release.