Hi there!
I've been trying to transfer the UE4 and UE5 mannequin control rigs to Character Creator 3/4 skeletal meshes actors but I cannot find and efficient workflow. 
I mean you have the UE control Rig, copy and replace the preview mesh with the CC actor, because having to create one Control RIg for each CC actor would be not efficient.
I try to follow this tutorial workflow but doesn't work for me:
https://www.google.com/search?q=UE+4+control+rig+copy&rlz=1C1CHZN_enES1065ES1065&oq=UE+4+control+rig+copy&aqs=chrome..69i57j69i61.7992j0j4&sourceid=chrome&ie=UTF-8
When I try to adjust the controls to closest bone the go to wrong places...
If somebody is making this work, please let me know.