Comparing documents that use Docproperty

I'm using Word 2003 on Windows XP.
I'm "happy" with comparing successive versions of documents to get the
change bars in the outer margin, and setting the options for insertions and
deletions to (none), and displaying Final showing Markup so that I can see
the change bars, but ...
We use a custom Docproperty named Issue on the title page and in the footer
of every page. When I generate the change bars, wherever this Docproperty is
used I see both the old value (e.g. 0.1d) and the new value (e.g. 0.1e)
together, with a correct change bar. If I try to resolve this by updating
the fields in the document, I get only the new value (jolly good), but the
change bar disappears (jolly bad). How can I get:
either (a) only the new value to show when I do the compare;
or (b) the change bar to remain when I update the field?
--
Ted