mixing two dispalcement shaders with node


well i try to mix two dispalcement shaders with node and material mixer.
all works fine, mixes fine when only colors are mixed.

however the problem with displacement is that it is actual geometry.
i somehow not need to mix the colors but the normal information of two shaders and i did not find any correct working node in blender.

is it possible in blender to mix two normal values together into a new displacement unite?

Ever find an answer to this one? ARE there displacement nodes yet?