P.S.: I would like to share the next step of exploration.
I'm not sure if you need this now or if I overshare here; my only indicator was the file, which is from a Learning version. If that is too much right now, back it up and consider visiting it later.
Please note, I left the Outer Controller out of this file, to have a clear view to the inner Controller only.
Please have a look at the file below:
CV4_2025_drs_25_CAik_21.c4d
This is the underlying tech of the inner Controllers (FK_Neck_IK_01_con+ to FK_Neck_IK_03_con+; while FK_Neck_04_con+ is more for the next step) #Spline IK Tag.
More in detail:
https://help.maxon.net/c4d/2025/en-us/Default.htm#html/TCAIKSPLINE-ID_TAGPROPERTIES.html#ID_CA_IKSPLINE_TAG_TWIST_CURVE
When you change one of the 01-03 controllers, you define the "Spline", which I have set to red here.
Feel free to move things around as you like, since I have frozen all coordinates. This means the Reset Transform will restore them to their original state when I froze them. Just pull one far away until you see the spline.
Screenshot 2025-08-22 at 2.18.41 PM.jpg
https://help.maxon.net/c4d/2025/en-us/Default.htm#html/43760.html
The outer Controller defines a kind of Forward Kinematic, while the inner Controller defines the flow or smoothness. Both in concert create either chaos or a smooth natural result.
All the best