I'm not sure that it's possible to do this without opening  the file.
The fact that you wish to access the information in workbook("A") means
that you have to open  it.
The question is: HOW must the file  be opened.
it MAY be possible to copy the file to .xla and open it as an add-in.
That way, the file isn't viewable, but MAY be accessible programmatically.
I haven't tried this, they keep giving me WORK to do!

After viewing your question though, are you saying that you don't WANT
to open the first workbook, or that you don't want to open it MANUALLY.
(meaning that you want the program to open it if it not already open).
Perhaps I'm reading more into this than is meant...