Mapping Center Answer:

The map that is shown within the data frame in page layout view must be the mapped area -- there is no way around that.  However, if you want to add an additional data frame to the page layout and show a different mapped area in that data frame, that is entirely possible.  Simply add a new data frame in the Table of Contents in ArcMap, and in the new data frame, add the data you want to show and set the extent to the area you want to show.

If we have misunderstood your question or did not address it properly, perhaps you could write back and send us a sketch of what it is that you want to achieve.