GLB avatar file - replacing head

I have a avatar glb file and a 3d scanned head in obj format. I want to replace the head of the avatar (glb file) with the head from obj file. I tried to do it in Unity but the GLTF utility requires a skinned mesh renderer which requires a skinned mesh (mesh with weight ?)

Then I read in a forum that Blender is capable of “skinning” a mesh. But I could not find how to do that.

How can I convert the “head” mesh to a skinned mesh with weight (and possibly bones ?) ?

I’d really appreciate if anyone could comment.

You have to rig it in Blender. This is a huge subject. I recommend reading up on rigging, weight painting, etc.

well, I just want to connect a head to the neck bone.
why does it need complex process ?
isn’t there any simple way of doing this ?

If you just want it on the neck bone, make it a child of the neck bone.

ok. I already did that and it works. but if I remove the original head , it does not export.
how can I add the new head and remove old head ?