Dear tflidd,
thanks for your reply.
in my case if i go for Federation Sharing configured on MainServer then i will need my officeServer to be online 24 hours , if it goes off then the links of the shared files will be unavailable.
users activiyies on the Federation Sharing over LAN wont be replicated on mainServer users activities.
the scenario on the bellow topic is what i need to do but its not solved yet 