File structure in SpaceClaim

I still have major problems with the file structure of SC. I really want to find
a way to copy an assembly with no associations to the original parts/assemblies.
When I copy/paste from the original into a new design I get my copies devided in
only parts, which gives a lot of work to make components/groups again. When I do
a "save as" it stll has associations with the original file.I think the problems
arise when an external subassembly is present. But when I try to convert this to
an internal it dissapears or I get an error "The operation is not supported for
an occurance". Can someone clarify this?

Regards,

Willem Wagelaar