Importing meshes into ue4 without combing

I tried to import an object, which has several sub objects, into UE4 from Maya. So I uncheck the “combine meshes” during the import process, however the meshes are all shattered into smaller files in the content browser as if they are totally separated files. They can be selected and dragged into the scene at once but they are not nested in the outliner. Why UE4 does this? why just not import it as a single file with the same hierarchy in Maya or Unity? UE4 was the only program that seems to do this, but why? Is there any reason behind it or is it a bug?

If you have separate objects in your 3D program and you export into a single file in UE4 it can only either have all of them as a single static mesh (using Combine Meshes) or it can separate it to different static meshes.
UE4 does not have a hierarchy like what Unity has, so when you import multiple objects it can’t place it as a prefab. It is possible though to take a set of meshes and make a Blueprint which will allow you to drop them in your level.