I've put in a request to share the same viewport in iC8 if you have CTA (Cartoon Animator installed) If you are asking about the ability to create Multi-legged/armed creatures in CC4 and iC8, then I recommend you vote for this; it's idea to more easily make it happen by the devs. Users may have to create a matching bone alias in CC4 if the developers can make it happen but Ideally if used cloned or renamed bone hierarchies  that match existing arms, legs etc the system should easily be able to switch to a different arm or legs set that was pre-created in CC4 but during animation/mocap time, switch to the bones that will be in use from the presets. 

https://www.reallusion.com/FeedBackTracker/Issue/Essential-Multi-Body-part-Characterization-Bone-Preset-Switching-for-Mocap-Edit-Motion-Layer-Motion-Correction-Puppet-Motion

Either by creating creatures from scratch or making bone name alias we should be able to do this without a major rewrite and I think would be a smart way to implement it. They may have started working on quad+ support from rumors i've heard but if not, I need more votes, it's likely better to suggest a easy way for devs to implement such request without having them think they  would need to rewrite from scratch otherwise we might wait years for a change.