Mobile Home Directory: Setting a relative location for various sub-nets

Question

Question Summary:
1) Is it possible to define a home directory for mobile account users that is relative to the host's subnet?
2) How does one accomplish #1 if possible?
Details
Setup
Users access hosts on three LAN networks connected through the WAN via Branch-Office VPN connections (persistant VPN tunnels that connect our LANs)
If User1 from LAN1 travels to LAN2, User1 has difficulty working, because the mobile account definition points to a host on LAN1 for HomeDirectory syncing, so all files are synced across a slow (5Mb/s) connection shared by all other users.  For some users (The CEO, for example), this sync entails transferring Gigs of personal data, so the Mobile Sync across the VPN literally takes several days, if it completes at all.
My ideal setup would allow User1 from LAN1 to access a host at a relative location as apposed to an absolute location.  In other words, if LAN1 has the home folder at 192.168.76.23:/HomeFolders/User1, then when User1 moves to LAN2, the HomeFolder becomes 192.168.78.23:/HomeFolders/User1. Regardless the subnet, the User account would be defined in such a way that the HomeFolder would be sought at 192.168.X.23:/HomeFolders/shortUserId
These home folders between the hosts 192.168.76.23 and 192.168.78.23 on LAN1 and LAN2, respectively, could be kept in sync during off hours so that at the beginning of each shift, all files are in all three locations ready for local use, fast access, and more importantly, fast home-syncing during the work day.
Equipment
OS X Yosemite running on various iMac and MacBook hardware configurations.
OS X Server 4 running OD replicas and local DNS's on each LAN.
Ample space for redundant data storage on all networks.
Question
How do I define a HomeDirectory as a relative location to the Mobile Account Users host machine or host machine IP address?
Alternatively, is there a way that I can define a HomeDirectory using a Fully Qualified Domain Name so that I can use the local DNS server to force the redirect?
Previously Tried Idea(s)
Using the same Bonjour Computer Name
On one test, I tried to trick the system by setting the name of the HomeDirectory computer to the same name on all networks. The thought behind this is that, when looking at the HomeDirectory path, the address is defined by the computer name, so if the local computer name matches, the system will automatically point to the host that is on the current LAN, as apposed to the host of the same name on the previous LAN.
This failed due to the fact that the system providing the HomeDirectory storage is the same system that is providing OD replica services, and OD replication requires that each system have a unique name.

Answer 1

Hi,
Yes my home directory is set
more /etc/passwd
sfsys1d:x:301:201:sys1 dev sftp user:/interfaces/dev/system1:/usr/bin/csh
when i log in they go to this directory, through a shell and through ftp ( haven't checked sftp yet)
However i can still go up directories and see what is in the directories above
the permissions are set as below
drwx------   3 root
sshusers  
3 Sep  6 08:38 interfaces
drwx--x---   3 root
sshusers  
3 Sep  6 15:49 dev
drwxr-----   5 sfsys1d sshusers  
7 Sep 19 14:52 system1
I have tried various other permission 700, 710, 740 etc and they all give different results but not the correct one.
The best I have managed to get so far is that they cannot list the files in the other directories, however if they know the names they can still go to them,  this also didn;t work in the windows ftp client, as it just showed the file/dirs anyway.
Thanks
Kerry