Mesh disengaged from socket after export

I attached skeletal mesh (shoulder) to socket (body) in another skeletal mesh in Character Blueprint, but when I exported the selected character in FBX, opened it in Blender and changed the pose of the body, shpulder didn’t move! How can I fix it?

In fact, I have to join in blender all meshes and weight paint them to achive result. It’s not good, I suppose.