don't delete existing files...

[Judith Flo]

Hi everybody,
I wonder if anyone could help me with an issue..

I have to sync several files from several computers "against" a
server. The particularity is that some users might have acces to the
server and can modify/create files...

The problem appears when a user, who has created a file in the remote
server (but that file doesn't exists locally), calls rsync with --delete 
flag.
That would delete the remote file in the server (too bad)...

I've been thinking a lot about that and i have some ideas, but i don't like
any of them... I know i could avoid using --delete, but would rather not 
doing it.
I could advice users to create files in the directories that will be 
syncronized.. and even force them to use diferents directories...
First, I could syncronized from remote to local (withour --delete) and 
then from local to remote (with --delete).. but in some cases, that 
wouldn't be necessary. Moreover, doing this automaticly would be 
dangerous (and i would like to avoid it).
Has anybody had the same problem? How did you solve it?

Thanks in advance!
Judith