Depends on what you are trying to do here.
Do you need the actual lines of the DWG or do you just want to have the information without the need to alter it?
For the first case:
It's like in Revit then, I guess. The DWG will clutter your file. Mostly line/fill types and layers.
The best advice here is to have a "blank template" *: a template thats literally completely empty. You can then open it, put the DWG in it, clean it, and then copy it without worrying into your main file.
In the latter scenario I would place the DWG as a drawing (shortcut: drag&drop the file to Archicad should do the trick).
You can still decide which DWG layers should be showing, as the pen set.
This makes it normally the good-to-go option.
* Masterscript.nl has an older version here
Mostly AC 26 on Mac | Author of SelfGDL | Developer of the GDL plugin for Sublime Text
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