Can you provide more details about the issue and what effect you need?
Couldn’t you just put all of the relays in the relays.dat file into the clientsettings.cfg file in a list?
Or why not set the client to do automatic relay selection, but have a few options in the failover list?
You could use the hosts file to point the root FQDN to the local relay. If you can control the DNS that the clients use at each site differently, then you could do something similar at the DNS level.
I personally primarily use the clientsettings.cfg file to set a bunch of client settings that will speed up initial provisioning of the client, as well as many that I think are a good idea in general.
It might be possible to handle the inclusion of relays.dat with my install_bigfix script: https://github.com/jgstew/tools/blob/master/bash/install_bigfix.sh
My install_bigfix scripts take a relay FQDN as a parameter and automatically set it as a failover relay for the client, so you could actually use this to get the desired affect already. The script actually works on Linux as well which don’t support clientsettings.cfg normally.
See the windows version here: https://github.com/jgstew/tools/blob/master/CMD/install_bigfix.bat
This is actually a combined version, which should work on Win or Linux: https://github.com/jgstew/tools/blob/master/CMD/install_bigfix_universal.bat
Original post about this: Script to kickstart the installation of BigFix on OS X, Debian-family, RHEL-family