I've read that often a modeler will create a blocked out version of a character to give to the animators so they can start blocking out the animation, instead of having to wait for the completed model.

The final character will have fingers and hair which will have several skeletal joints. However, the blocked out version has no hair and no fingers so it doesn't make sense for it to have the extra skeletal joints.

My question is this: Can the basic animation of a simplified skeletal system be easily transfered to a skeletal system with more joints, which the animators can then create animations for the fingers and hair? Is that typically how it's done in a pipeline where animators use blocked out versions to start working on the animations?