Subdivide and re-weight parallel/sibling bones? (or, how to deform-rig lips) I have several lip bones, as shown. They are not linked to each other in a chain, but share a parent and grandparent (maxilla and head).

Each non-corner lip bone is weighted generally like this along the length of the lip:

I would like to have more than 3 bones per lip between the lip-corner bones for finer control of the mouth polys (e.g. 4 or 6). Is it possible to subdivide parallel/sibling bones and redistribute weights between them? Alternatively, can someone point me to an effective way to rig lips (not Rigify plugin because I don't know how to export that)? Thanks!
You can simply select the armature, in edit mode use shift D to duplicate some lips bones, place them where you want them (the duplicated will have the same parent-child relationships), then in pose mode select all lips bones, go to object mode, shift select the mesh, go to weight paint mode and use the weights menu &quot;Automatic assign from (selected) bones&quot;.
Make some manual weight adjustments if  needed.