Not currently. If you attempt to, the file will tell you that the current
dwg is already associated with a project.
The best way I've found (and I can't believe I'm typing this,) is to use
data shortcuts.
I'm with you, I think it shoudl be an option, and I can't think of any
reason it can't be done.
You might have some other ideas posted if you post in the C3D group.
--
James Wedding, P.E.
Engineered Efficiency Inc.
www.eng-eff.com
www.civil3d.com
C3D/Vista/2GB