[Samba] DOS/Windows Archive bits, and file ownership

[Greg Sloop]

Preamble:
I've done a lot of looking round news-group archives etc, and I haven't found a definitive answer on this question:

My environment:
Clients are all Windows boxes.
Assume backup of the "share" is a Windows based client. It relies on
the DOS Archive bit to determine Diff/Incr backup selections. (User
Execute bit in Linux)

Goal: Allow users to "own" their files and allow for "automagic"
modification of the archive bit by non-owners of the file when they
modify the file using the Windows application or by the backup
application.

Example:
Joe creates a file called "JoeFile.txt"
Joe is listed as the owner, but the group is "AdmGroup" for example.

Fred is also a member of "AdmGroup"
Thus, Fred can modify/delete/etc "JoeFile.txt"

The problem comes when we look at the archive bit. 
As above, Fred can modify "JoeFile.txt" even though he's not the
owner, but he can't change permissions and modify the archive bit.

Create mask on the share is: 770 (I know, 760 would be sufficient for just the archive bit, but I'll take the system bit too, a long as I'm here...)
This will allow the owner to change the archive bits, but no-one else.

I believe I've tested, albeit a while back, the "dos filemode" parameter too.
IIRC, it would allow you to manually change the archive bits, by going
and setting the properties directly - say via Windows Exploter.

It wouldn't, however, allow for the applications, at least for those
that I tested, to change the archive bits on files unless the user
doing the modifications was also the owner.

---
I have ways around this, by using "force user" for the whole share,
but this really seems like a brute-force way to do things. It also
makes it impossible to determine who really owns the files, and who is
killing us on space - which always happens.

Further, the force-user there are other reasons which I won't bore you
with, why I don't care for "force user."

---
So, is this a live-with-it, as-designed bug that I just have to work
around, or is there some more elegant solution that I've not
recognized yet? (Or, perhaps more likely, have I just missed something
really stupid that I'm doing wrong.)

If more details are required, I'll be glad to provide what's needed.

TIA!
Greg