The body and nose models are separated.
The body and nose models have mixamo bones with the same name.
The nose model does not have any animation data.
I tried to play the nose animation using the body animation data, but it does not work.
I got this system long time ago, but now I have a case where the model has different body proportion. The structures are very similar as they both use mixamoRig. But the animation, if shared, will produce strange movement (as expected, since they are different proportion).
If I try to use the retarget function from SkeletonUtils, this is what I get: