trouble updating links to master files
 

I want to share inventory information in real time. One MASTER will update
inventory and 4 VIEWERs (VIEWER1, WIEWER2, ... VIEWER4) will view changes
made by MASTER. All 5 files are on the same server so all 5 users can have
their respective files open at the same time.
MASTER makes changes and VIEWER files have links to MASTER. Theoretically,
as soon as MASTER makes a change and hits <enter, all VIEWERs should see the
change immediately. This scheme works flawlessly when I have MASTER and a
VIEWER file open simultaneously but when I have someone else change MASTER, I
have to fool with the formula in the VIEWER file before the data will update
to the new value. I tried manually updating the links but this didn't help.
Any suggestions?