I was trying to follow this super complex rigging tutorial on how to rig the human head and face

and i got to a part where you use blendshapes to control the lips of your rigged head and the other blendshape head with the lip control things, they're skinned using splines

problem is, whenever i try to apply the blendshape to the heads, it never seems to work right

the tutorial says that i should use the front of chain deformation order, but whenever i try to use that, the rigged head kinda shifts up as seen in the video

not certain how to fix this