This question applies more to Microsoft Word, but maybe
the procedure is the same for Excel too.

Suppose one document is open in Word. If you click on
File-Open and open a new file, is it possible to have that
new file be opened WITHIN the current document? In
other words, inside the new document at the top of the
already opened document?

Or, do I need to string together a bunch of copy and
paste macros to insert another document into my
already opened document?