How to Include 'jaw' Joint and Eye Joints in a Kinematic Chain?

[XGraphKhipu]

Hello,
I am currently working with a kinematic chain represented by lists of joint indices in Python, similar to the following example:

t2m_kinematic_chain = [
[0, 2, 5, 8, 11], # pelvis --> right_hip ---> right_knee ---> right_ankle ---> right_foot
[0, 1, 4, 7, 10], # pelvis ---> left_hip ---> left_knee ---> left_ankle ---> left_foot
[0, 3, 6, 9, 12, 15], # pelvis ---> spine1 ---> spine2 ---> spine3 ---> neck ---> head
[9, 14, 17, 19, 21], # spine3 ---> right_collar ---> right_shoulder ---> right_elbow ---> right_wrist
[9, 13, 16, 18, 20] # spine3 ---> left_collar ---> left_shoulder ---> left_elbow ---> left_wrist
]

Now, I want to include the 'jaw' joint (index 22) and the eye joints (indices 23 and 24) into this kinematic chain. I'm unsure about the connection between the 'jaw' joint and the 'head' joint (index 15). How should I modify the kinematic chain to include these joints properly? Should I connect the 'jaw' joint directly to the 'head' joint or consider another approach?

Any insights or suggestions would be greatly appreciated. Thank you!