Save dgn to dwg

Apologize if the question is answered. I went through almost all discussions about this topic, however, I couldn't understand the following:

Saving dgn sheet and respective design models to dwg produces a dwg file with all sheets in paper space and separate design models. All dgns referenced to the sheet file are merged and presented correctly in paper space. so if I want to edit anything in AutoCAD, I can do it by working in paper space. Is there a workflow or variable that forces dgns not to be merged but linked as an external reference to the sheet model in paper space?

To be more clear. I would like to have a sheet model in paper space (plan and profile sheet or cross-section sheet), where all drawings are presented as external reference files, and any edit I may need to do to any of the sheets, I would prefer to do it in respective external file. 

Thanks

Nikolin