[AccessD] Query becomes uneditable

I have a fairly simple query, with a people table, with outer joins to
tlkpState on stateID etc.  It is editable as it sits.  

I need to provide a county population of the county for the zip code in the
address.  I have a table of zip code information which includes this
information, however the zip codes are not unique, i.e. there are
potentially multiple rows for a given zip, for reasons like the name of
suburbs inside of a "town" etc.  Because the zips are not unique, the table
has a "primary" field which holds a "P" in the field for the "primary" zip
record.  Don't look at me like that, I did not do this!!!  This table does
not have a PK of any kind, probably because it would be extremely difficult
to discover a natural key, and an autonumber is less than useful anyway.  To
make matters worse, we get an update to this table periodically.

I have a query that pulls a single record per zip based on a "P"rimary field
which holds that "P" in that field for exactly one record for each zip.  If
I join that query to my updateable query on the zip, my query becomes
non-updateable.  If I join the table itself on the zip all hell breaks loose
as you might imagine.

Is there an answer to my quandary?  Is there a way to get a zip / county
name out of this table, joined to my query while still having the query
updateable?  The county field should not be updateable anyway.

I think I could just put a subform in that displays the county but I am just
wondering if there is a "cleaner" way.

John W. Colby
Colby Consulting
www.ColbyConsulting.com