I export step files from SharkFX since this the only way the objects retain their names.
Often I boolean unite objects that does not touch, like the four legs of a table, in order to reduce complexity. However non-touching objects that I boolean unite in SharkFX import separately and loose their original names. I wonder if it is a limitation in the step format or a bug in either application.
Btw I strongly recommend everybody to check out the 3d apps Viacad and SharkFX (same thing simple and advanced versions). It's the best cad modeler at it's price range.
Claus