How do you manage multiple /etc/passwd files?

[zemon at felix.UUCP]

I just installed my third computer which means that now I
have three /etc/passwd files.  So now I'm trying to figure
out some way to relieve my users from the need to update
passwords three times when they want to change them.  How
do you do it?
-- 
	-- Art Zemon
	   FileNet Corporation
	   Costa Mesa, California
	   ...! {decvax, ihnp4, ucbvax} !trwrb!felix!zemon