Combine meshes, but rotate one first. At runtime.

I need to combine two meshes, at runtime. One of the meshes, I need to apply a rotation to and combine it with the other mesh.
Imagine attach an arm to a torso, pointing forward. Then, attaching another, raised upwards.

I need to actually apply the rotation to the mesh, then combine it rotated with another mesh. I’m hoping there is a way to do this in blueprints, and not have to drop down to C++.
Any ideas?