Question Humanoid Skeleton with Additional Animated bones

Does anyone know how I can use Humanoid Skeleton with a rig that has additional animated joints?

I have a character that has extra bones for a scabbard and sword. I want to use Humanoid Skeleton with it, but that means that the extra bones are ignored during animation.

This is meant for a pipeline with characters that have animated apparel and weapons etc. Also, imagine someone has a very cartoon character with a giant animated hat and other appendages. Is Human Skeleton just not suitable for these kinds of rigs?

https://imgur.com/e285DSK

https://imgur.com/I5dj0d6
Here you can see the two additional joints. They're greyed out.

https://imgur.com/dOj4AE6
In the above image the sword should be in the hand and the holster should be getting pulled along

Thanks either way and regards,
Stefan

 

I tested this some years ago to animate a tail, then I didn't use it anymore so I can't recall well how it worked but it is possible.
I remember however clearly that it's not possible to do a retargeting(using different skeleton structure) so the bones in the animation and the bones in the humanoid skeleton MUST have the same name and hierarchy, they may have position and rotation but then the animation may look wrong since it's simply applying the same rotation as the animation file.
Some things to try that I can think of:
-If you clicked optimize game object make sure you expose these additional bones.
-Check the animation window when it's playing the animation and see if it's failing to find the property there, or if it's not there at all.
-Can't remember if I also tried to export additional bones as an another animation and played that as an additional layer with a mask, but I think it should work without this.