Hi. My suggestion is to add bone rigging and bone adding to cc4. I have attached image examples of the bones and areas of interest.
Right now it seems the only way to import a unique custom character that works is if its been rigged with cc4 in mind. I have tried importing characters into cc4 that or in t pose and some that arnt and set them as humanoid and creature and neither one gets the results of bones, infact its almost like they have no bones at all. I beleive this is because the bones need to be named correctly to work within cc4. This create a big problem for artists who might want to create something more unique to what is already there, such as adding a tail to a current model then rigging it in a external software such a blender. The adding bone for the tail wont work unless its attached and named correctly. cc4 should have its own bone rigging system where the user can add bones within the software, such as adding a bone that has the funtionality of a tail to the bottom of spine. The power to add these unique bones with spring animations and more could bring the character more to life than before and allow artists to really create something unique.

Adding a spring animation to the bottom area would create a realistic movement of the bum when it walks.
adding a spring or some kind of bone to the sternum/chest area could create a breathing animation.

Users could buy from the shop unique bones that they could add to any current model within cc4

tail bone with spring animation
hair bone for pony tail animation (could also be applied to characters that dont have hair but have additional head attachment such as tentacles)
breathing bone for realistic chest/torso compression animation
extra bones, adding bones to current model to deform the shape of the model into something else, such as dog bone femur altering the humanoid leg into that of a dog.

I hope anything I have said in this post helps and gives food for thought.