If you want to use a real 3D editor for creating OpenPose poses, there is the option to use Blender with the MPFB addon. There is a tutorial for this at http://static.makehumancommunity.org/mpfb/docs/openpose.html
With this approach, you can pose multiple persons in one scene and have the ability to export JSON with COCO and optional hands coordinates.
If you need an introduction to MPFB, see the getting started video at
