I've researched this subject extensively recently. Here's what I've
uncovered so far.
1) Your best bet is to name any cell to which a link refers. If you do
this, you don't have to worry about all linked workbooks being open. If you
have many links, I recommend a very simple naming system such as NAME and
then the cell designation (example, NAMEA1 or NAMEC37). If you do this, your
problem will be solved.
2) As a much more difficult alternative, (and as you pointed out in your
question), you could make sure each separate workbook is open before you make
any relevant changes. If you only have 2 workbooks to deal with, not much of
a problem. If one sheet is linked to 100 other workbooks, where multiple
users are involved, you'll have a problem. I've uncovered a macro that will
automatically open all linked workbooks so that you don't have to do it
manually, but it's still a pain in the you know what. Let me know if this
helps!

"George P" wrote:

I encounter similar problems, sporadically though. I too am curious for an
answer. Thanks for posting Beth!

George

"Beth S" wrote:

I have a link in a formula to an external spreadhseet. I'm getting an error
unless the source workbook is open. I've never run into this probelm before.
Any suggestions to fix so I don't have to always open the source?