You could save the other workbook with its windows hidden, then either use a
macro to open it:
Option Explicit
dim OtherName as string
Sub Auto_Open()
dim OtherWkbk as workbook
dim OtherPath as string
otherpath = "C:\somefolder\" '<- note the trailing backslash
othername = "book99.xls"
set otherwkbk = nothing
on error resume next
set otherwkbk = workbooks(othername)
on error goto 0
if otherwkbk is nothing then
'it's not already open
on error resume next
set otherwkbk = workbooks.open(otherpath & othername, readonly:=true)
on error goto 0
if otherwkbk is nothing then
'still didn't open
msgbox otherwkbk & " wasn't opened!"
end if
end if
end sub
'close this workbook when the "real" file closes????
Sub Auto_Close()
on error resume next
workbooks(othername).close savechanges:=false
End sub
(Untested. Uncompiled. Watch for typos.)
