So far, you've learned how to apply the Skin modifier, adjust envelopes, and adjust vertex weights manually. When applying the Skin modifier to a character mesh, there are a few additional considerations.
If two or more mesh parts are going to use the same skeletal structure, you can apply the Skin modifier to all the parts at once. For example, if your character's upper and lower body are separate objects, you can select both objects and apply the Skin modifier to both at the same time. This creates an instanced modifier on the modifier stack, where changing Skin parameters for one object would change them for all objects to which Skin was applied.