I have a tree of about 20 NW 6.5 servers. Currently I have a single
reference server (FS1) pointing to an outside time source and all other
servers are set up as secondary servers pointing to FS1 for time.

I need to change the single reference server to FS2. What is the best
way to do this? Is the following the best order?

1. Make FS2 the single reference and point it to the external time

2. Make FS1 a secondary time server and point it to FS2.

3. Modify the timesync.cfg files for all other servers so that they
point to FS2.

Would the above cause the least disruption?

It looks like the timesync.cfg file is not server specific. Is there
any reason I couldn't modify it once for FS3 and copy it to the
sys:\system of the other servers, then do a timesync restart on all of