Openfire across multiple locations

Hello Everyone,

I am looking for a little advice. Lets say I have about a half dozen locations and I would like to give each site an openfire server. The reason behind this is that we have WAN problems from time to time. If a site goes down (and they obviously lose contact with the exchange server) it would be nice to keep production up through IM. Under normal circumstances both would be used, but if one fails the other one is a fall back. Right now we have one OpenFire server at one site, using the most modern build, and using LDAP authenication. Initially I was going to use Server to Server connections, but that makes managing groups a real pain (Multiple users in the same department at multiple sites). Basically I am looking for a way to allow each site to have its own Openfire server for local stability, but can be easily managed as if it was one single server.