Animating 2D character inside the editor?

I wonder whether it is possible to animate 2D character (puppet) which is composed of several subobjects (head, torso, legs, …) right within the editor, and blend between those animations.

So far, I discovered that Matinee is able to offer some in-engine animating options, but I can´t figure out how to blend between different Matinee animations (e.g. walk, idle).

Is this even possible to do or one must use external 3D editor?