make first(most common) model with skeleton and bind skin, export mesh and joint hierarchy, import in UE as usual (create skeleton for it if needed first), then with same skeleton bind skin for other mesh and export only joint hierarchy and freshly binded mesh, when import choose already existing skeleton.
now when time comes for animation, you just animate using your rig, then export only joint hierarchy without meshes selected, import it as animation for previous skeleton. easy.
UE4 skeleton cares only about joint hierarchy and names, as long you don’t move/rename joints it is same skeleton(though you could make another instance when importing).