Question about Referential Integrity in Microsoft Access and Postgres tables linked tables via ODBC

Hi,

I've recently become owner of a project to slowly replace a complex and
much entrenched Microsoft access application with a web based application.

Moving to a web based solution in one step is not politically feasible
at this time. I am handling this one table at a time, keeping Microsoft
access as the fronted, until I get to the point when all my data resides
on the postgres server.

However I have hit a snag that I do not know how to cope with.

In the Access file we have two tables, say "Course" and "Student", that
have referential integrity between them. On the client side in the
"Course" table this gives the user a useful in-line editing, via a
little + sign that expands to a row on the "Student" table, when editing
the table.

I have come to the point where I need to move the "Course" table to the
postgres server so I can display some of its information on the web. I
exported the data to a text file, imported it to the postgres server and
linked the table to the Access file via ODBC. However I can now not
create a relationship with referential integrity between the linked
"Course" table and the "Student" table, which means that I lose the
useful and much used in-line editing facility. From the reading I have
done it looks like Access will not allow referential integrity between
tables on different databases.

Does anyone have any ideas on how I can create the "referential
integrity" or if there's a way I can simulate this so it appears the
same to the user of the Access file?

with thanks

Christian