Thanks.
Now that's better. The internal formats and mechanisms of a level is unclear to me. From what I can think of now, the "standard" structure of a WMP should normally contain 3D objects like: a terrain (HMP), level entities (WMB) and normal model entities (MDL). If I make the level (the terrain and the blocks) in a 3rd party soft, how would WED know which to convert to HMP, which to WMB, or MDL?