I'm probably missing something real simple...but here goes:

We are using Zen 6.5 SP1a
XP sp 2 workstations.

When are Windows group policies additive?

I have created a User Package that pushes down workstation and security settings to the workstation. It is associated to a "User A" with a DLU present. That works fine. When I log in as that user all the settings are there and correct.
If another user logs in ( say "User B") to the same workstation, that does not have Group policy settings in effect, that works fine as well. The settings from "User A" are still present..so far so good.
Now "User C" has a minor tweak on the computer settings ( not a security setting because those are not additive) in his User Package. When "User C" logs in, all of the settings applied from "User A" are gone...and even the minor tweak for "User C" is not working???

Does this work for Workstation Packages only?

If it works for User packages ( which is what we use ) are there criteria for making it work properly??

Thanks in advance