Not quite sure what you mean by copy a retention policy to modify a small portion? You can create a new one but no copy and paste functionality as it were.

It sure would be nice to copy an existing policy.  Creating a new policy to exactly match another, to change a few settings or meet new requirements can be time consuming (and costly if not set up properly).

I agree.  Why not post this to the Ideas section on this Symantec Connect site.

FYI:

I fooled with this quite abit last year and the short answer is it may be possible but it will not be worth the effort.  In sql there are not only mutliple columns but the advanced settings are stored as rows in another table.

Consider upgrading to EV 8 (which has the copy feature) if this is a must.

-Joe

 Note, you can copy POLICIES in EV 8, but not retention categories.