Mesh not welding in custom character rig

I have a problem with a custom rig imported from blender, welding doesn’t work, I tried using scripts, using WeldConstraint but it doesn’t work

help I’ve been trying to fix for hours

Character:

Issue:

Issue photo:
Screenshot 2024-12-12 153226

Try using something like a motor6d or a bone.

each mesh cannot have more than a single motor, and being a custom rig it already got 1 for each mesh

Then set it as the C0? If the head is being affected by the torso then make the hair be affected by head? This way each has one motor 6d???

im confused, can you show me an example?