I am recently adding a company field to an existing application.
I have the company linked to a supplier and a customers table.
Because of the way the application currently works, I can't simple link both tables to the same company table without getting a circular join 'thingy'.
I know there is a way (using macros) that if the user selects the company field on the customer, it will also select the same company on the supplier table. Its been a long time since I had to do this, and can't remember how its done.