[Samba] Shared Samba locking system

[Sh4d03]

Hi all,

I'm wondering whether it would be feasible to share the Samba lock file 
between two Samba servers. My implementation will be similar to this:

I have two sites each with its own OpenBSD 3.8 Samba Server connected 
via OpenVPN over a "not-so-good" link. Ultimately, the link isn't too 
bad however the users are often calling on large file and crashing 
Mircrosoft Programs as they're not designed to wait that long. My plan 
is to run rsync between the two servers (in both directions) to 
synchronise the data. This will probably be done on a 5 minute basis, or 
maybe 15. My issue from here is that when file "foo" is opened on Server 
A, there will be no lock in place on Server B to prevent simultaneous 
editing. Obviously, the effect of this is that I have two versions of 
the same file and rsync will simply blow one away with the "newer" one, 
despite the "older" one possibly having new data.

My intention was to share the Samba lock file "live" across the VPN 
using maybe NFS or some other means. I've been reading up on the locking 
system of Samba in an attempt to ascertain the ability to do this but 
would like to open it to you guys for advice. 

Alternatively, if there is another option that people can suggest for 
doing what I need I'm open for suggestions.

Kind regards and thank you in advance,

Sh4d03