It’s strange that this answer isn’t available.
It seems I need to create a dedicated AnimBP just to keep rotating one bone.
However, AnimBP requires strong skeleton compatibility and will refuse to reuse any structure that is even slightly different. Therefore, i need to either copy the same AnimBP and apply retargeting, or create something similar from scratch.
I don’t want to do any nonsense like this because I just want to rotate skeletons with the same name with the same logic. Does anyone know any other good ways?