What options are there to keep two way syncronization on samba servers?

For example.
4 remote branches and 1 main branch

Have one samba server at each location and keep all of them in sync with eachother.
If usera on branch1server changes a file it is also reflected at each of the other branches. I can think of a bunch of problems with this as if 1 branches netowrk goes down and it gets out of sync what happens whens its network connection is restored?

I would think there would have to be a master server at a single location and everyone connects to it and then have one failover server kept in sync with an rsync cron every minute or so type of thing?

I would think rsync is the best way of doing this.

Thats what I was thinking of, has anyone here tried the clustering service available from redhat?