AutoCAD Civil 3D :: Hydraflow Import Changes All Parts To Standard Style?

one would think that you could just export the .stm file into hydraflow, make some changes, and import, and all would be fine.  when i export, all of the structures in hydraflow come up as drop curb.  how can they come in as what they actually are.. aka, when the part i use is a 2x4 box, it should come into hydraflow as a "grate inlet", or a st-mh will come in as a "manhole".

and then likewise, when the changes are made, and its brought back into autocad, they all come in as a "standard" style.  except the outfalls, which show as a "standard" style, but come in with a different block, and get a whole new label (outfal - x)