What do you mean by “not linked”? Is it on a different layer? If it’s still within the same layer, you can assign its parent to the desired bone. Alternatively, you can export the origin of the parent, then for the child bone’s origin, apply an ‘add’ converter and link the rhs or lhs to the previously exported bone origin.
The only way that I know know of for “linking” familys of bones([parent+childre] to [parent+children]) is moving them though a group. Sonic RubberHose Walk.sifz (40.8 KB)
I did that in my latest Rig project.
Warning: Disable the loop layer; kind of heavy to preview.
Hope this was informative.