[Orgmode] archival mirroring source headline structure?

[Adam Spiers]

I just discovered `org-archive-save-context-info' - very nice!
especially the preservation of the outline path (olpath).  Though it
might be even nicer if archival could optionally auto-vivify outline
paths and archive sub-headings under them.  So if your source file
had:

    * PROJECT foo
    ** NEXT bar

and you archived 'bar', it would check in the archive file whether
'foo' already exists, if not create it, and then archive bar under it.
So after incrementally archiving many sub-items to do with a single
project you would have all the sub-items gathered under that headline
in the archive file.  Is this doable now, and if not would it be hard
to support?

Thanks!